If you want another example, imagine you're putting a piece of furniture together. You see there are screws provided that need to be put in. The instructions say you need a flathead screwdriver. Would it be reasonable to assume you can use a crosshead screwdriver instead? After all, it's also used for putting in screws, so why wouldn't it work with the screws provided? It's not like there's a disclaimer saying specifically that crosshead screwdrivers don't work with flathead screws.
Yep, so you'll be wanting a scroll or NPC then.In any case, heal is easy to come by in a high magic campaign, but in a low magic campaign you'll be out of luck for several levels. And that's assuming you have a traditional cleric in your party. Druids have to wait for their 7th level spells to get heal, while a sorcerer/wizard has to wait till 7th level to cure Feeblemind, then has to pay 300 XP to cure a 5th level spell that costs nothing for their foes to cast.
And yet it's not in the defined list of spells given that will cure feeblemind, which says to me that it won't work. If it "The subject remains in this state until a heal, limited wish, miracle, wish spell or similar spell is used to cancel the effect of the feeblemind.including these spells", then I'd agree with you.To be clear, if it said 'only these spells' or it said 'Break Enchantment will not cure' then I'd be inclined to rule your way. But Break Enchantment is a spell designed to dispel Enchantments of any duration, even instantaneous, that are 5th level or lower. Feeblemind is a 5th level Enchantment of instantaneous duration. It's squarely in the bounds of spells Break Enchantment was meant to effect and dispel.