Yes you are right - I was just thinking, what RTAs would mesh actually fit in? Many/most have the deck above the juice channels, so it needs a wick that can bend. You could use mesh, but then you would need to put some cotton in each end to go from horizontal to vertical. There could still be some small advantage in that - to change juice, dry burn the wick in the coil and then just replace the end pieces of cotton. But it is not as good as just having a single wick, and maybe not worth the effort (depends how long it takes to make/re-make those cotton end pieces.)
Actually the Squape is one example that might work. Here is my SXK Squape Rs clone deck:
So it is pretty much horizontal - and I think it would work with mesh.
Don't worry about the thread, we have been OT for a couple of pages

I will post some more Squape stuff shortly hopefully