Yeah, no. If they want to be OP, make them mod for OP-ness. And the idea that mages should be OP demigods? Why do you think WOTC nerfed them so heavily in 4 and 5e? Because I'm pretty sure they weren't meant to be that, or people were just finding them unfun as fuck.
Also, struggling to do something as one class while another can do it with just the flick of a wrist, with no way of knowing which is which is not fun in my opinion. It's just stupid game design. Gaming as power fantasy has never appealed to me in the least (well, at least not since I turned thirteen, but at that point things were easing off in my life, so I wanted more challenge).
As long as there are many OP options, and the multiclass in 5e allows for that, it is way more fun than everyone being "equal" which equals boring.
This. Exactly.
Incidentally, I followed the link.
I know the edition wars are over but here goes

People who think wizards were OP in 3rd ed had DMs who weren't applying the rules as written. Once a wizard starts casting everyone gets a free attack of opportunity -- including the tavern owner who can only swing a pint of ale. Unless the wizard somehow manages to avoid getting hit (and how would they) and have to make concentration check. If they somehow make that then spell could be counter spelled by another mage. Mages pretty quickly learn that casting in combat isn't a great idea and it's better to create wands so you can actually get a spell off. And so the wizard quickly becomes the fantasy version of a gunslinger. And it's hard to level up a 3rd ed wizard -- every wand costs experience points and the rest of the party will soon ask the wizard to create magic swords and the like. So you can look at the spell list and say "wow, these spells would really dominate the late game" but -- unless you have generous DM -- wizards a) have a hard time getting to a level where they can cast those spells b) have a difficult time casting them.
Now the 5 step corrected this some but it was immersion breaking -- so my halfling mage can stretch her suddenly elastic legs through two goblins to make to safety? Of course I'll use it but it doesn't really make any sense . . .
DOS2 actually did this better by making attack of opportunity a feat that one needs to take.
In 5th edition wizards have fewer spell slots but they have a much greater chance of getting a spell to fire.
Anyway, not to bash on 3rd. 3rd was okay but 5th is better.