Why is WWW. no longer used

Why is www. no longer used.

WWW before domain names used to be common www.corpsie.co.uk. for example but this has dropped off in favour of standard subdomains.

mysteryhour.corpsie.co.uk is a subdomain of corpsie.co.uk as is theorycraft.corpsie.co.uk

We just decided to drop the www as we no longer said world wide web and the www became meaningless