Not sure about the person you replied to, but here in northeast US if you don’t mow to keep trees down you can quickly end up with a very thick growth of trees. It’s also easy to end up with a lot of undesirable (invasive) species crowding out the native/desirable plants.

It may be the case that a small amount of trees is beneficial overall for pollinators but if you’re managing an area as described then it takes a bit more work to plan for trees and mow around them.