I don't want 100 different SharePoint sites. How to create private teams w/o a new site?

Guys. WTF. I've inherited a problem where a company of 50 people has 100 sharepoint sites - because users created different Teams for different projects, and Microsoft makes it incredibly opaque what this actually means. Now we have 100 SharePoint sites, many of which are unused, but all of  which appear in the list of sites in 365AC. 

The structure we WANT is 1 Sharepoint site for our 1 org, but multiple locations within that site, and multiple groups for multiple projects. I THOUGHT what could work was converting the excess Teams into Private Channels. But I have now learned that private channels ALSO create SharePoint sites, because _______. Most confusingly, all of these sharepoint 'sites'  DO exist within our main SharePoint website - they're just pages (but not 'pages') pretending to be a fresh sharepoint website. This confuses the **** out of people, the way they've redefined what a 'site' is, what a 'team' is, etc. 

This is genuinely hot garbage, and it's suddenly clear to me why people always push back on using SharePoint over OneDrive. Recommendations for... not having this disaster? Making a structure that is intuitive and doesn't redefine what a site and page are, and allows you to have private locations for management or projects, but DOESN'T create a 'site' within the main 'site', with it's OWN 'documents', and it's own 'Notebook' (which isn't a document) and it's own 'Conversations' (which are NOT conversations), and it's own 'pages'? I don't work with dumb people - these are very technical people. But even our main SharePoint guy is mystified by these interactions. 

Does it make more sense in another language? 

If anyone at Microsoft is reading - the english term 'site', comes from the word 'website', which generally refers to a distinct web service with a distinct domain name. These contained different webPAGES.. When websites started existing off a shared domain name, like company1.sharepoint.com and company2.sharepoint.com - this confused people, but they put up with it, because it was relatively easy to explain the tech behind this - having websites under a single site, that wasn't too hard to understand. But what SharePoint seems to do, is extend this practice into absolute hysteria, where a particular webPAGE of a webSITE is ALSO a site, but also is a TEAM, or COULD be a CHANNEL. OR it could be a PAGE - WHO knows? If it's a TEAM, that TEAM could have CONVERSATIONS, which aren't actually Team Conversations - they're EMAILS. But this is fine, because all CONVERSATIONS of a TEAM done in TEAMS are actually stored as EMAILS so really those, CONVERSATIONS should be CONVERSATIONS...   So why aren't these conversations in Teams between a Team that are stored as Emails not showing in the Conversations which show emails within that Team? aefggaddadsfasd