I'm pretty sure I used a desk with a sloping top at school in the late 1980s or early '90s. It looks like it was probably 30 years old though.
Form memory it was ok to write on, great to read on and terrible to put thing on. But it had a self underneath where you kept things (and could hide novels to read during class).
Yes, some old pitched school-desks were definitely hanging around in the '80s, but my impression is that their manufacturing was another casualty of the '60s/'70s. (That seems to be when the two-seating, flat, Formica-surfaced table came in as school furniture: so modular! so modern!)
Form memory it was ok to write on, great to read on and terrible to put thing on. But it had a self underneath where you kept things (and could hide novels to read during class).