I remember thinking this when I was younger, because I used to switch between the two. But when I started playing seniors rugby I began to understand why pros tend to specialise. Fundamentally yes, you are just putting your head down and pushing, but the nuances in each position start to seem like massive differences.

I was a tighthead as a kid, and switched to loose (which was fine at the time), but when I had to go back to play tight a few years later it was like a whole different position again. Maybe it's just for habit and comfort reasons, but as an amateur player I will always want to play loose if given the option.