Nope, Clerics had stat requirements for how high a level spell they could cast too, and also no, you had to have an 18 to do 9th for wizards and it dropped down 1 spell level per stat point all the way to 9 int which was the minimum requirement to qualify for the class.
Clerics also had bonus spells and had sphere access.
I love when people flat out make a "factual" claim without actually knowing if they're right or not. I don't actually know where my 2e PHB is. I have my DMG in sight, but no idea where my PHB is. I will say that I don't remember minimum stat requirements for cleric spells. Not saying you're wrong, but I'd bet you are. If you can prove it, I'd be impressed.
As for Wizard spells, you actually are wrong. My main character was a Wizard. Created in Basic D&D (as an elf) and moved up through 3.5. I know, it doesn't drop down 1 spell level / stat point from 18. Fact is, a 16 AND 17 INT gave access to 8th level spells. I believe it dropped down 1 spell level / 2 stat points until it stopped at INT 9 at 3rd or 4th level spells. Again, I can't put eyes on my PHB, but it's not what you think.
Clerics did get bonus spells for high wisdom so at least you got that right. We house-ruled that wizards got bonus spells for high INT that mirrored the cleric's.
I do have my 2e PHB handy, so I checked:
- Chuck has correctly described the rule for determining a wizard's maximum spell level. INT 18 allows for level 9 spells, INT 16/17 allows for level 8 spells, INT 14/15 allows for level 7 spells, etc. INT also determines the wizard's chance to successfully learn a spell (35% at INT 9, +5% for each additional point of INT) and their max # of spells known at each level.
- There is no limit for WIS-based casters in terms of the highest-level spell they can cast, but there *is* a percentage-based chance of spell failure for casters with a WIS lower than 13 (it starts at 5% at WIS 12 and reaches 50% at WIS 3). Bonus spells are available for priests with WIS 13+.