VisThey go half hp because it's easier to just hold M1 4-5 times than constantly maintaining as highest hp as possible while still building
I understand why they do it and yeah it is easier to do it like that
But the problem is as a medic when the enemy team decides to dry push or sac somebody and you have a 80hp pocket scout who is bleeding and feel compelled to heal him
Plus it's not that difficult to maintain 150 constant hp