Old Benoni Defense Accepted Similarity to Giuoco Piano

I recently discovered the Old Benoni Defense (1. d4 c5) and found it quite interesting. While exploring the Accepted Variation (2. dxc5), I tried to play natural moves and noticed something surprising:
After just five moves, the position closely resembles a Giuoco Piano, except for two key differences:
1. There is no Black pawn on c7 and no White pawn on d2
2. It’s Black’s turn to move
Black is missing a c-file pawn, while White is missing a d-file pawn - meaning White has lost one of their central pawns, whereas Black still has both. I also checked the evaluation bar, and interestingly In the Old Benoni Accepted, the engine gives 0.0 (equal) and In the Giuoco Piano, the engine evaluates it as +0.2 for White.
almost as if both sides played the Giuoco Piano but now black got an extra move AND a better pawn.
Given these factors, it seems like Black has a very playable position, so why isn’t this opening more popular? Am I missing something?

Old Benoni Defense

Giuoco Piano

Because almost no one will play the moves you showed in Old Benoni Defense Accepted.

And they are slightly worse than the best move. White is not gonna play this opening so it's so rare to achieve that position.

If your opponent knows how to play against Old Benoni Defense Accepted, White will still have the advantage.

After 2. ... e5, the engine shows that Be3 is the best move for White, even if White doesn't play it, there are other good moves instead of the ones you showcased.

And even the Bongcloud can be a good opening if Black plays slightly worse moves than the best move.

That's why it's not that good and this position is unlikely to occur in a real game.

thanks for the response!
when d5 happens, it becomes the declined, which have its own lines.
but i'm discussing the accepted, which we can assume would be pretty popular against the old benoni defense since taking the pawn is the natural move.
i played 2. e5 with black and not e6 because i wanted to get a center pawn and thought that it can get to similar position to the Giuoco Piano...
engine shows me that both 3. Nf3 and Be3 are +0.3 to white and both seems pretty normal tbh
regarding 4. Bg5, i actually can't see why it is considered good, since black can just play Nf6 and now if white want to bring the bishop back to e3 to defend his pawn, he wasted a move because he could have done that one move earlier and black got to develop his knight with a tempo... and after 4. Nf6, the engine shows that white best move is 5. Nc3, which letting black take the free pawn while developing his dark squared bishop... and in this situation although this is not the Giuoco Piano, black still has 2 center pawns while white only has one, with a nice position for both sides.
so i think the Giuoco Piano position is still reachable within the Old Benoni Defense and if not - this is still a very nice position for black, with only +0.4 advantage for white, similar to the advantage in the Sicilian Defense and other famous openings.

"only +0.4 advantage for white, similar to the advantage in the Sicilian Defense and other famous openings."

This makes no sense. No sense to talk about "only +0.4 advantage". For one the Sicilian is based on accepting a concession so it has counterplay. Secondly they are completely different.

Otherwise, yes it does look a bit like the Guico Piano but looks even a bit superior one for white, though the computer doesn't seem to agree. It seems because it's black's move and he gets to play Nf6 and castle so white is a move behind from the usual attacks he might try like Ng5 and they no longer work.

i said "only +0.4 advantage" to show that the computer evaluates it to be about even, i didn't talked about the nature of the opening nor compared it to the Sicilian and didn't claimed they are similar in a way. i pointed out Sicilian to show that similarlly to how the computer evaluates the position in the Sicilian as +0.4 for white, it evaluates it to be +0.4 for white in the Benoni as well, i tried to show that the +0.4 is negligible, and that the opening can be considered good
though my main point is that if it is a solid opening, why isn’t it popular

Old Benoni Defense and Benoni Defense is pretty popular. But not much compared to other responses to 1. d4. There is better openings and people choose to play them over Old Benoni Defense and Benoni Defense, that's why.

well i checked databases from multiple websites including chess.com Explorer and i saw about 16k games in which the c5 move was played as a response to the d4 and litterly 17 games in chess.com database of playing e5 after dxc5

Okay but I'm not sure someone argued against that.

After looking on lichess I think the answer to your question is because white rarely plays dxc5. Only in 4% of master games does white play dxc5. And the computer gives d5 as +0.7 vs cxd5 as only +0.1 So white will rarely play the "Old Benoni Accepted" and if he does it's probably a mistake, but when they do yes positions like that can occur.

The old benoni fell out of favour compared to the modern because the modern benoni induces white play to c4 in addition to d4, with the move c4 being a bit of a wasted tempo for white. So if white simply plays 2. d5 and doesn't play c4 at all he's getting a better benoni than if he plays c4 like in the modern benoni.

If black is known to only play the Benoni, it might be worthwhile as white to delay c4 for a while and not respond with it immediately after 1. d4 Nf6, hoping for black to play c5 anyway and getting an old benoni.