Actually, as a whole, I'd say magic was VERY underpowered in Oblivion, you can't call magic overpowered when you need 15 fireballs to be able to kill the average enemy at higher levels, but there were a few spells that were kind of overpowered, chameleon, most notably, due 100% chameleon, invisibility though, I wouldn't say it's that overpowered, because it dissappears as soon as you interact with an object or attack someone, which is a pretty big problem if you want to use it for say, stealing objects in plain sight without being caught. And charm? All it does is make people like you, how is THAT overpowered? It's not like people will fight for you just because they like you or anything, of course, it probably helps that Persuasion Overhaul is one of my essential mods, and it makes persuasion much harder (No longer can someone with level 5 in the persuasion skill raise a character's disposition to 70 just by playing the minigame a few times.) and anything that can help me raise their disposition is a few times. And frenzy? I guess you could sort of argue that's overpowered since it can allow you to kill anyone without needing to worry about getting a bounty, still, in Morrowind, there was a taunt option in persuasion that could do that without even taking into account their level, frenzy, I seem to recall, has a limitation to level upon it. And I don't see how you can say open lock is overpowered, all it does is OPEN LOCKS, you know, something you can do just as well as a thief, in fact, lockpicking was a better option for opening locks than the spell in Oblivion, because with lockpicking, you can open any lock no matter what your skill level if you're good at the minigame, with unlock spells, you need a higher level spell to open more difficult locks, which requires a higher skill level, if anything, the SECURITY SKILL is overpowered in Oblivion, but you're right, you don't need to train lockpicking in Oblivion, because even if you don't, you can still pick locks. Or is it that by your definition, anything that lets one class do something another class can do is automatically overpowered? Should we remove destruction spells then since they can allow mages to fight? After all, why train weapon skills? And paralyze? What, should anything that *gasp* let's players use tactics to gain an advantage in combat rather than just clicking away and hoping that their mindless hacking away at a target proves stronger than their enemies? Because paralyze is above all a tactical spell., and it's not like you can just use it on every enemy you see and never have to fight again, most paralyze spells have a short duration, and I seem to recall, a high magicka cost and skill requirement, not to mention it's possible to resist them, sounds like enough of a limitation to me. And what about silence? It renders any mage hit by hit COMPLETELY helpless, but I guess that's fine because mages are "overpowered" anyway.
And how is it that you didn't even mention the resistence spells, reflect spell or absorb spells, or reflect damage, which could potentially make you COMPLETELY IMMUNE to damage of a certain type?
But I don't want ANY of those spells to be removed, whether they're legitimately overpowered or not, nor should they be made into scrolls, because that's removing features to fix balance issues, whether real ones or percieved, and usually, the preferable solution is usually to make changes to the overpowered features rather than removing them. If you say chameleon is overpowered, than just cap it so it's impossible to get 100% chameleon, the same goes for resistence, absorbtion and reflection spells.
Thieves werent overpowered becose mages could go running with invicibility and do THE EXACT SAME THING ONLY 10000 TIMES EASIER!
Warriors werent overpowered becose mages could go and paralyze their opponents without taking a strike AND KILL THE SAME GUY 1000000000 TIMES EASIER
Right, I don't recall killing enemies with magic ever being even 2 times easier than with weapons in Oblivion, if I didn't use any mods that brought mages up to the power level they SHOULD have, in fact, it was harder, a good sword or mace killed enemies better than magic, and didn't have limited ammunition, not to mention armor only reduced the damage of weapons, unlike magic resistence, it didn't make enemies COMPLETELY immune to all mundane damage, reflect damage could make you immune to melee damage, of course, but high levels of reflect damage were a lot less common than resist magic or elements. And mages shouldn't be so much weaker than other character types, because why would anyone use magic if using mundane means is a lot more effective? I agree with the post you quoted, mages have powerful supernatural abilities, and these should be shown as something impressive, which they were not at all in past Elder Scrolls games, now, for the sake of game balance, you can't make mages TOO powerful, but making them WEAKER than the already are is not the solution.