I do the same thing, I'd assume a lot of people do. My API is at version 87.2.19, while my user-facing app (that nothing programmatically accesses) is 1.3.4.
If you maintain software that only humans interact with and does not need to be programmatically read, there is no reason to use semver.
On the flipside, I've long argued that maybe its time we deprecate/remove user-facing version numbers and there's no reason to use "romver" other than (decades of) momentum.
What does a "romver" really tell a user? "A number incremented from the last time you used this software." That's about it. It doesn't tell the user anything about what new features might have been added or bugs fixed or anything they actually care about. You can get a lot of the basic "number incremented" gut feeling simply from "Release Date", and that at least is something slightly more user concrete because they can look at a calendar and get a feel for how old a version is or how long between two versions development took, which is slightly more interesting.
Really though, "romver" itself is often just as meaningfully useful to users as "random fuzzy animal" or "random sugar snack" keywords, and those are at least more "fun". We can market software versions with other things than dotted sets of maybe sequential numbers.
It's not a battle I often win though, but it is something to think about. Numbers are great for machines, but they aren't very human, and why bother presenting numbers to people?
It's a good point. It really depends on who your users are. The "users" of my apps who would ever see the version numbers are people who need to know version numbers, and romver works fine for that. The actual end consumers of the software don't see version numbers because, like you said, it doesn't matter.
It does bother me that Apple and Google force you to have version numbers shown in their app stores and it's shown to the public. I push OTA updates for my apps quite frequently without going through the stores and I've had some users ask why the app changed without the store version number changing, and I've had users ask why the number jumped from 1.0.7 to 1.3.4 with no updates in between. "Because I didn't have to submit updates to the store for the past two minor changes but I've updated the app icon so now I have to" is difficult to explain to say the least.
If you maintain software that only humans interact with and does not need to be programmatically read, there is no reason to use semver.