Wizards don't even get full access to their spell list, they get a truncated selection that, if they're lucky, can expand via found scrolls. Even if they had access to all of their spell list, the issue becomes which spells to prepare. People always talk about "why have X class when a wizard can just cast a spell" but if the wizard doesn't have the spell, say knock, prepared then it doesn't count for anything. Add to that the resource cost of expending a spell slot and I'll bet that any wizard would love to have a rogue available to pick any locks the run into.
Wizards gain a lot of power at high level, except those high level spells are once a day, if you only need those spell slots once a day, great, but if you've used your one 9th level spell and then have another encounter where your one 9th level spell prepared would be super useful, too bad.
I like wizards, probably my favourite class in any edition, but people often make out that they are super powerful (in 5e) when instead, they're just powerful, so long as they have spell slots available and maybe a day to prepare that spell that would be really useful to have right this minute.
