>power armor is basically just makeing a human shaped tank,
A human shaped tank that can fit through doorways, climb stairs, etc. Something a tank shaped tank can't really do. And of course, tanks are (more or less)limited to fixed weaponry, whereas a dude in power armor can just put down whatever he's carrying and pick up something else.
Power armor isn't replacement for tanks, it's replacement for special forces infantry. At least, assuming suitable power sources can be developed.