Because wikipedia long ago decided that 'notable' had a fairly low bar. There's really no going back now and personally I very much like the abundance of articles, even on relatively minor people/companies/events. The storage/serving costs for these articles is negligible, but the value to our society (and maybe especially future ones) will be enormous.

Some language versions have higher requirements for notability. It's hard to set a clear cutoff point for example in sports, entertainment and companies. When does something become wiki-notable? Everyone has their own admins, deletion policies and arbitration mechanisms, which have and will influence content.

Statistics show clearly that some have opted to include as many stubs as possible via the use of bots (for example Swedish wikipedia). Tens of thousands almost worthless stubs (like all US townships and communities) could be machine-added at any time, but most wikis have steered clear of this kind of doping. German wikipedia is quite the opposite in regards to pictures. They don't allow any fair use / citation pictures, which leads to de.wiki articles having considerably less photos than other languages.

What good are any of our acts if they aren't recorded for others to see? /s