Everyone gets treasure. Saying that someone can burn a significant amount of their treasure, that everyone can do, doesn't say much about what's special about their actual class.
Especially when the rogue needs to spend more of his treasure on his weapon(s) and armor than the wizard for basic functionality, so is behind the ball to start.
It's less obvious in a group that is not diverse and uses more random treasure. The DM goes "You find a wand of bark skin" and no one can use it, so the rogue goes "Well, I need a 10 on the die, but guess I'll take it". In my experience, that's fairly rare and that's effectively party treasure anyways. The rogue can eventually pick up, say, a wand of fireball, but it'll be with a horrible DC 14 and only 5d6 damage, at a point when the campaign has moved onto DC 22 12+d6 damages (or flat out save & suck).
But, sure. In infinite treasure land, the rogue does awesome with use magic device. In infinite treasure land, use magic device is so awesome that _everyone in the party takes it_.
That's just talking about the UMD skill.
That's not talking about all the other skills, plus class abilities like Uncanny Dodge, Evasion, Special Ability, Sneak Attack, etc...
These conversations are all about what "can" be done so the Wizard doesn't get to be the only one who enjoys that spotlight.
If we are going to trow in those limitations that actually happen in real life games then the same needs to go for the Wizard. Not all Wizards have just the right spell memorized, monsters who are standing in the right place, fail their saving throws, magic shops, having time to actually buff before hand, finding other spells besides your 2 per day etc...
I could say that a Wizard is highly dependent on certain things happening but every time that's mentioned the old "well it could happen" excuse pops up.
You can't turn a blind eye when it comes to the Wizard arguments but focus like a laser on other classes.