Maybe harsh.
Let me try this:
If you are a programmer, you might have been taught to indent 5 spaces for each differing line of code. At some point, you have to work on an application where they use tab. You don't like tab. You go to a different project where they also use 5 spaces.
In this case, the licensing might cause full-stop. Apple chose FreeBSD because they don't have to give their changes back, but if it's significant, they might want to, or else they have to maintain a separate group of code that they have to add back in with each iteration, and do their own regression tests to ensure the changes didn't break anything.
If you work on one system during the day, you are familiar with it, and continue using it at night.
Your neighbor uses <system blah> which means you can get help from them.
With the Linux distributions I pointed you to, one might come with KDE pre-loaded, and another has Gnome, but what about the folks who still cling to icwm? That's just for windows managers. Each application might have multiple versions, and folks like one for particular features or whatever, and not another.
The problem is that the license really might mean that you can't do your daytime work on a given system, so you pick one over another, and put your efforts into that.
Now, if you consider the sheer number of people working on the total different distributions, it really does seem a _might_ bit much, and figure that more could be accomplished if there were fewer choices. The problem is who gets to decide which ones? You might like something, and I can't have it for whatever reason. I'll work on mine while you work on yours.
For fun, I logged into
www.github.com. I did a search for "meal nutrition planning". I got 53 results. 53 different versions of programs that all help you plan meals and nutrition. They are in multiple different languages, some haven't seen an update in years, and some have active development.
Does that make sense?