I think it isn't, there are other (free) ways to make and mass download collections/new maps. Personally I use osu!alt bot to make my own, which isn't the same as a collection specifically made by a human, but it's good enough for me and it doesn't miss any maps with the parameters I want. Not easy to single out tech maps and such in this way other than stealing maps from tech players tho, so osu!collector still has some niche