Why not instead first identify what sort of sharpening one seeks to do and on what sorts of blades, and then pick a stone based on that?
Good question - The answer being that it’s not that simple, but to an extent people get to do what you say, perhaps not on their very first set of stones because they’re mostly focused on grits of a progression and «what’s good at such grits for money », but eventually as they gain experience they will remark for themselves : my 4K is nice with carbons but sucks with semi/super steels, my coarse thins well but I hate having to sharpen from it, my mid doesn’t give me as much feeling as my two others etc. etc.
That’s when you get in the second zone, and it’s not only the kind of edge wanted for a given steel/use, but sometimes wanting to reciprocate the feeling of another stone they like better but different grit, or wanting a S&G because they finally hate having to soak first, and etc etc.
Also it’s all hearsay - what a stone does best. Not written on the box. Here the hearsay is quite developed and tangible, but still perhaps a member says something about a stone like « it’s so good to get such edge on such steels, and also to do such kind of work on such steels. What he doesn’t say however, because the situation doesn’t call for it, is that he perma-soaks. Now you take the advice, get the stone, but your time is always limited and you simply soak it - not quite long enough to top that. Nothing of what the member told you works for you - because conditions of use are different but you were not aware.
It’s an example, perhaps a bit long-winded, but it comes to say that to do what you suggest is hearsay, depends on other factors than the stones like also technique, and that they are many options available.
That’s when you start just wanting to try some specific stones not so much for a specific case, but because they are considered remarkable in their range and you’re just mostly curious, and then other stones seem interesting for very specific use only and you won’t know until you try it, and there goes the rabbit hole.