Nothing is supposed to be real. But many things are supposed to be realistic beacuse it adds to the enjoyment of the game. Too many unrealistic things and the world becomes weird and people suddenly can't relate to it and lose interest.
I wouldn't say I need economy in my games realistic, but it needs to be internally consistent.
I prefer silver standard because its more realistic than gold standard, at least on the surface.
I agree.
Of course in an old-school dungeon-based game of D&D the world economy is hardly important, only the PCs equipment matters, and even 3e system of assumed wealth-by-level works without problems.
Economy, including magic items market (prices, availability of magic items for purchase, ease of selling loot...), becomes important when you want to advance your game into taking place in a world that makes sense, which is typically (tho not necessary) the case for long campaigns. That's where PCG-like simple economies start to feel wrong.
Then there is the purely narrative fairytale-like gamestyle, where you want your PCs to find the unbelievable treasure in the dragon's hoard, and not destroy the game with it so that you can continue with another adventure.
I think the current idea of 5e of making no assumption about wealth is the absolute
best approach, because any other approach would cut off other gamestyles. If the starting point is
no wealth required, from there you can add a "module" (can be a virtual module, i.e. no real need for written rules) that works for old-school/PCG-like gamestyle, for realistic/consistent world-building gamestyle, for purely narrative style.