I partially agree, it can quite often be an overkill.
Before I started I bought a camera, it was important it shot 4k. Today I don't even use 4k. The big files and editing just makes it a nuisance to me. I know that in some payed programs you can substitute the 4k footage with lower res, to make it easier to edit, but I can't in what I want to use.
These are my stats.
There is a huge difference. Highest amount of views are from phones. But people on TV have more than twice the watchtime.
I do think, if all my videos were 4k instead, it would have improved the stats for TV and PC a little.
For someone who is already making travel videos, if that person already have a decent 1080k camera, I would recommend a cheap drone as the next investment, before a true 4k camera. (!!!Depending on location, as drone laws can be very strict!!!).
If you are making a lot of scenic travel shots, then no. It's not overkill. But there are likely other investments (time or money), that would be more helpful long term.