It's true that obstructions above the ground level would decrease the distance you can get line-of-sight to the next tower at the same tower height (a 40 m pole-style tower could have only 20 km LoS to an equally tall tower with 30 m tree cover vs 40 km for no tree cover, meaning 4× as many to cover the same area; effect is less if you use taller lattice towers at one end or both, of course) but it also decreases the range you can get out of the connection from tower to UE, not exactly to the same extent, but close enough. The change from GEO to LEO for satellite backhaul means that satellite is more technically competitive, sure, but microwave backhaul is possible, at least for basic mobile service (I would not want to use it for fixed wireless without even more tower density)... if you wanted to blanket even the mostly empty land between the two towers with good mobile coverage, which is way more towers than what most MNOs would want to purchase.