I think the bigger issue is the variety of distros that end up not being compatible. Even if you overall have a lot of Linux users if they, for the sake of argument, distribute evenly between all distros then it’s still a lot of effort to code. The only difference is that the argument will change from “Linux has a small userbase” to “Distribution X has a small userbase”.

Linux doesn’t just need more users to be worthwhile to develop for, it also needs a distro agnostic solution to run software. That or significantly reducing (or streamlining) the amount of distros so the developers would have far less configurations to account for.