It doesn't matter how many tags it has heart is still a really ambiguous tag name. Like seriously if you went onto the street and asked people what a "heart" was i'd bet a grand majority of them would describe the organ.

And it's not like there's no precedent for adding disambiguators to fairly massive tags like most of the *_(artwork) tags have them despite the fact that most of them 3d_(artwork) for example is tagged ~100 times more often than what it's being disambiguated from (stereogram). There's also similar cases, like gold_(metal), and how all of the mlp characters have them to distinguish the pony versions (*_(mlp)) from the human versions (*_(eg)) even though the human versions are a pretty rare sights on here (and I don't think all the characters even have human versions).

It seems to me that having disambiguation suffixes is, in fact, the rule rather than the exception where as cases like mario not having one is the exception.

EDIT:

I'm sure people can handle alphabetical order...H isn't exactly at the end of the alphabet.

When you're trying to get through a large tagging project you're only going to be glancing at the tag list not reading through the whole thing. You're going to be looking for tags you know are commonly missing, general tags that have less than 10 or so posts, and tags that don't apply. It's really easy to glance and see tags at the beginning and end of the list, tags like the year tags (20xx), anthro, anus, <3, cum, and breasts are usually the fist few tags, so when they're not there it's pretty obvious, same thing goes for vaginal, white_background, transparent_background, sex, and solo which are always going to be the last few tags. Everything between F and R is going to be somewhere in the middle depending on how many tags a post has, it could be fewer than 10 tags from the top it could be more than 30 tags from the top. Mind you you're looking for tags that aren't there more than things that are which is usually a bit harder for the human brain. And you're doing all of this as fast as so you can get to the other 50+ tabs you have open filled with other posts that you're adding tags to for the tagging project you're doing.