Carbonation level, does it really matter?

I’ve been doing this for a year. I brew for myself, family, and friends.( no competitions). Every time I do an extract kit I get to the priming sugar addition and it’s always the same “2/3 cup of priming sugar”. I’ve been using the priming calculator offered here and depending on the beer temp, type, and volume it can really vary.Why doesn’t the kit instructions just tell people to reference their online calculator if it is that important or am I overthinking the importance of proper carbonation?

Proper carbonation makes a difference, although some people might be put off with a lower level so I think the kitmakers include a standard amount. Also it keeps things standardized from a product standpoint, and simple from a consumer standpoint. You should do your research and use the proper amount of sugar for the right carbonation.