> Are there any games nowadays that allow such things and spawn so many custom maps?
WC3 literally spawned DotA, and thus the entire genre of MOBA. It was originally just a WC3 map.
SC2's editor is also quite capable - the game is free to play, there is a lot of cool stuff in the arcade section, with some very active minigame communities (Direct Strike, Crap Patrol, etc). Sunspear Games are making Immortal, a new RTS which was initially prototyped using the SC2 engine; these same guys earlier did StarBow, which could best be described as "StarCraft 1.5", with many good elements of both BW and SC2. And of course there's that guy who's remaking all of WC3 in the SC2 engine, and it works better than WC3 Reforged (which I sincerely do not recommend to spend your money on). There's also the SC2 Mapster Discord server, some people are trying quite interesting things for regular 1v1 maps (considering how conservative normal 1v1 is), like water slides, destructible resources/watchtowers, etc.
Overall not the golden age, but it's very much alive.