I agree completely. Those "unsound openings" were not unsound until the GM's studied them in depth; Good for them, they have to know them backwards because it's their careers.
The Kings Gambit became suspect when Fischer said d6 beats it.
Now we have beginners saying it is flawed.
I'd challenge anyone below Elo 2000 to beat it by playing d6, and boy can it be a lot of fun.
Even if you stuff it up as White, it still gives you lots of chances.
The best way to improve is to attack and learn from your mistakes.
Example 1 Slav exchange now very popular at high GM level as they are now skilled enough to extract the tiniest of advantages and see it through the entire game.
Club players cannot do this and for all intents and purposes for them the Slav exchange is just boring type of equal
Example 2 Catalan So very trendy now, even 1200 rated players are talking about playing it. GMs have the super technique again to extract the small advantages from the position
Club players on the other hand it can just end up a rather boring middle game where both players stumble around making a succesion of small positional errors.
Club players are better off playing the openings that the GMs avoid. Aggressive openings that are not quite so good at GM level because their opponents are super good defenders and will beat off a big attack and expose weak squares, or a doubled pawn of some other small advantage
At club level your opponents are not super defenders, chances are you send your h pawn down the board and it strikes gold. Pawn storm, opponent overwhelmed. Obscure lines of Four pawn attacks hit home. Unsound gambits, are not unsound when every other move is sub par.
The object should be to give your opponents as many problems to solve as possible, and the GM openings are generally not the best way
Or am I talking garbage