Reason to not play the Najdorf

You have to prepare against 6. Bg5, Be3, Be2, Bc4, h3, f4, f3, g3, a4, Bd3, Rg1, Nb3, h4, a3.

Or that means White is struggling to find a good move.

Only 6. Bg5, 6. Be3/f3 and 6. Bc4 require a deep move by move preparation.

You've correctly identified one reason why I recommend against the Najdorf at below master level... due to a6 not applying pressure or vying for central control immediately white is free to respond in enumerable ways.

Another problem with the Najdorf is it's the most common sicilian there is. Meaning that if white has anything prepared against any sicilian at all, it's going to be this one. That's not how you want to play at levels below masters.

Also, while the Najdorf is considered the most objectively sound line, the moment you try to deviate in even the slightest way you're right on par with any other sicilian in terms of your objective position. Meaning in order to justify your decision to play the Najdorf you really must play just the most theoretical (and predictable) lines as deeply as you possibly can, otherwise you should have gone with something else.

I guess you know how popular Fischer's 6.h3 currently is, no?

Even minor sidelines like the positional 6.Bd3, or the tactical 6.Rg1 require a lot of preparation to avoid bad positions.

Or something like 6.h4, which is practically unexplored, and usually creates positions which do not look like Najdorf, at all.

6. h3 was very trendy 10 to 15 years ago, less so now (if there is a trendy line now it's actually 6. Bd3).

6. h3 e5 7. Nde2 h5 and 6. Bd3 are positional lines where Black won't be blown off the board, it's nothing like having to learn everything move to move to avoid a forced loss after 6. Bg5. They belong to typical structures with e5 (or 6. Bd3 g6 which is also typical). There is general knowledge to build and concrete applications to master, sure, experience to gain through the games and the years, but that's not a lot of preparation, that's simply called learning to play a main line opening correctly. The Caro-Kann, the French and the Spanish are just as demanding.

As for 6. Rg1, if you're running out of ideas or can't bother to prepare you can play the cop-out line 6. Rg1 e5 7. Nb3 Be6 8. g4 d5 9. exd5 Nxd5 10. Nxd5 Qxd5 11. Qxd5 Bxd5 12. Be3 Nc6 13. 0-0-0 0-0-0 14. Bb6 Rd6 which is close to equal. That's probably not what you want in an ideal Najdorf world but you won't lose from the opening and therefore 6. Rg1 doesn't *require* something special. Black gets into trouble only if they want to.

as someone who plays the nydorf i know the pain

Against 6. Bc4 I played a prepared novelty in a country vs country match... on move 28.

Kids, don't try this at home!

I disagree. I played the Najdorf as a newcomer to tournament chess and I am glad I did.

Yes, White has many options at move 6. But Black does NOT have to memorize lines against each. Black’s development (e6, Be7, b5, Qc7/b6, Nbd7/c6, Rc8) and counterplay (advance the queenside pawns, pressure the c-file) will be the same regardless of White’s development.

yes, there are some move orders by White that require Black to be careful about his move order. But this is chess. And if Black makes a mistake and gets crushed, he will learn what not to do next time.

What is important for beginners to learn about openings is the general development of the pieces and the subsequent middlegame plans. They should NOT be trying to memorize move sequences.

Except, you don't get to play the Sveshnikov. You get to play against the Rossolimo instead.

I played it religiously from the time I was 1400 OTB (Canadian CFC rating).

I've only played in two actual FIDE-rated events, a Canadian Open in the early '70s and a Canadian Junior around the same time - all the rest of my OTB play was CFC rated, not FIDE rated - and the Najdorf was played in both of the games where I scored points in one event, and in half of the games where I scored points in the other event.

It served me pretty well. And some of my opponents were (for the '70s) pretty well prepared.

I am aware you don't have to play the Najdorf in the theoretically ideal way, I just don't see a benefit to playing it this way over playing any of the numerous other sicilians ... at this point the Najdorf is just a relatively passive and universally known line. If you're just playing chess now - why not the Taimanov, or the Accelerated Dragon, or even the Classical or Four Knights...? You don't have an objective edge over these lines anymore, once you chose to abandon the main Najdorf theory. At least with these other sicilians they make some attempt at controlling the center early, i.e. white doesn't have 10 different testing responses you've got to grind and memorize.

I suppose you could deep prep against all of these.

I'm lazy, though, and I'll usually just play 6 ...e6 in response to all of them. Easy-peasy lemon squeezy.