"If the goal of the opening is to get to a playable middlegame, the Evan's is no better and no worse than any other opening. You get to a position where White has good center control, more space, and easy development for the cost of a pawn."
No, you don't get a better center control, you don't get more space, and black gets at least as easy a development as white's in the Lasker line - which is precisely the reason I don't suggest playing the Evans' competitively.
"If your goal in the opening is to squeeze out every advantage you can, then sure, most gambits are not going to work for you."
I apologize for being the bearer of the sad news, but that's how consistent results are achieved at the master level.
"However, if the assertion is that you cannot play the Evan's Gambit above a certain level because it becomes dubious (which is what the question was implying), that is incorrect. It can be a lot of fun to play (at any level) and is one of the more sound gambits available - far more so than things like the Grob, Blackmar-Diemar Gambit, and Danish Gambit, just to name a few."
I never said the Evans' is plain bad. On the contrary- I clearly stated that it can be a really fun opening. I myself have played quite many games with mixed results - but the games were always very entertaining.
Spassky and Bronstein in their time used to play the KGA successfully against top-level competition (and there haven't been many new theoretical innovations in the King's Gambit since the 60s and 70s), although it is well-known that black has many adequate lines to achieve easy equality. The problem for their opponents (including Fischer) was that at the board it was possible to play only one of them!
After losing to Spassky in the King's Gambit in 1960, Fischer wrote an article "A Bust to the King's Gambit" in which he claims that the King's Gambit is busted and loses by force. If you plug in his analysis with modern engines, he evaluates the positions out of the opening as roughly equal (a far cry from "losing by force"). The irony is that a few years later he played a few games in the King's Gambit from the White side (using the Bc4 move order) and won all 3. It would seem that even he did not believe his own claim that the KG was refuted.
Similarly, the argument that the Evan's is 100% sound just because world-class players have (also very rarely) used it against players of the same level is not quite convincing.
That is not the argument. The points being made are the following: 1) it is not dubious (meaning it does not put White in a worse position - as the position even after the pawn sacrifice is roughly equal), and 2) that it has been played even at the very top level (which goes to the OP's question). Just like with the KG, Black can hold with proper play - which is the same with any sound opening. No one would claim the Ruy Lopez is unsound, and with proper play from both sides it is a draw. The fact that the Evan's Gambit gives up material (gaining space, time, and central control in return) and leads to a draw with proper play indicates that the opening is not unsound.
My (objective) opinion is this - If the opponent is prepared for it (ie. they know the good ol' Lasker defense), then there is no point in trying to play for an advantage after the first 6 or 7 moves as white, against equal opposition. Otherwise, it can promise powerful attacking positions with pretty miniature wins in store for you if you're lucky. So it becomes a particularly effective as a surprise weapon [at all levels], but I wouldn't recommend making it your main Italian Game repertoire.
If the goal of the opening is to get to a playable middlegame, the Evan's is no better and no worse than any other opening. You get to a position where White has good center control, more space, and easy development for the cost of a pawn. If your goal in the opening is to squeeze out every advantage you can, then sure, most gambits are not going to work for you.
I agree with the last statement (not making it your main weapon), but it does not hurt to have it in your arsenal. At the US Open several years ago, there were a LOT of Evan's Gambits being played in the 1200-2200 rating ranges, with many decisive results. In fact, it was probably the second most played opening that tournament (the London sadly being the most popular - at one point when I was walking around, there were 2 whole tables of boards where every single game was the London).
Of course, all this is for serious otb chess competitions. On the internet, there is no pressure whatsoever and the main point is to have loads and loads of fun playing chess
Agreed. However, if the assertion is that you cannot play the Evan's Gambit above a certain level because it becomes dubious (which is what the question was implying), that is incorrect. It can be a lot of fun to play (at any level) and is one of the more sound gambits available - far more so than things like the Grob, Blackmar-Diemar Gambit, and Danish Gambit, just to name a few.