Harvesting Trees for Timber

Is this the expected behavior when I try to harvest a tree?

If I am mounted, I click on a tree and watch the cast bar channel, then the game says "You are Mounted" and the harvest fails, while the tree becomes non-interactive so that I can't click on it again--for a while at least.

Is that how the game treats everybody?

If so, why does it work that way?

If I am not allowed to mark trees for harvest while mounted, why doesn't the game dismount me when I click, the same way it treats herb and ore nodes?

If I must dismount manually, why doesn't the game warn me so before it makes me watch the cast bar that's doomed to fail?

If I must dismount and waste my time watching the cast bar, why can't the tree I'm trying to harvest stay active, rather than completing the insult by more-or-less despawning.

The whole process is really off-putting, since most other similar game mechanics work differently are are less punishing.