Is hot air only meant for desoldering?
It's not really a misuse to use a hot air hand rework station for soldering parts, but it would be uneconomical to solder whole boards with it in a production setting. Getting consistent, high-yield results when soldering hundreds of SMT parts by reflow requires careful control of the time-temperature profile, which is very difficult to achieve with a hot air gun. It also involves exposing various components to repeated hot-cold cycles as you move the gun around the board, which is punishing treatment for them - most are only rated for 3 or so reflow cycles.

For prototyping purposes, if you don't want to use a proper reflow oven or the cheapie toaster oven equivalent, the best bet is probably to solder all parts with leads using an iron and a drag-soldering or flood-then-wick technique. Use the hot air gun only for the bottom-terminated components, and accept that your yield isn't going to be 100%.