I more usually use distress inks, but certainly I use my Winsor & Newtwon AWC paints and Twinkling H2Os. It most certainly is a technique you can use!! I still have some watercoloured cards from my dad from 30 years ago and more. You will, ovbiously, get the best results stamping on watercolour paper. Try and find one with a fairly smooth finish or it will be hard to get a good impression from the stamp. Up till recently I was using a W&N AWC cold press, but I found some Rowney Hot Press at a good price and it's certainly a smoother finish. But less detailed stamps give a good impression on the cold press, and there are times I like the rougher finish.
I used watercolours for this just a couple of weeks ago: ODBDSLC137 Surging Sea by Cook22 - Cards and Paper Crafts at Splitcoaststampers
And here's one by Marie-alice which has been in my favourites for years: Ladybug Lou-la-Bella by ladybug91743 - Cards and Paper Crafts at Splitcoaststampers
You can also use them to make wash backgrounds - great look: Splitcoaststampers - Watercolor Wash Technique Tutorial by Beate Johns
Combine that with heat-embossing for a resist look (and some metallic pens like leafing pens also work as resist, as in this card:
ODBDSLC17 Summer Colours by Cook22 - Cards and Paper Crafts at Splitcoaststampers