Yes, in my experience Theoretical Seating applies to Row 1 just the same as anywhere else - seeing TS blocks there is very common.

On one recent flight I was the only passenger in Row 1, at least by allocation (Another passenger was moved there by the crew once we were all seated), I guess there are various reasons people don't take row 1 including

- Don't want to put bags up at takeoff/landing
- Prefer the room to stretch out legs under a seat over the better kneeroom
- Travelling as a couple and only 1 seat free (likewise for bigger groups)
- Simply don't know it's available

And many others besides. I always try to remember the wise words of c-w-s and others that really, we are the weird ones on this forum (I'm sure he was more diplomatic) and for a great majority of infrequent travelers, people just do whatever the airline tells them. So if they get allocated 4C, they go sit in 4C.

I do notice that people informally move to Row 1 occasionally when it stays free after boarding, sometimes checking with crew, sometimes not.