so let me get this straight. hbo aquires sesame street (an educational television show that was publicly broadcasted and free that has impacted millions of children), put it behind a paywall, and has now taken 200+ episodes off of its service which are now effectively “lost”

Not quite, for Sesame Street this is the HBO deal:

  “Sesame Street” will still be available for free via the public airwaves – but on a delayed basis. Episodes will become available to PBS stations and web sites nine months after they’re on HBO. 

Basically the only people who “lost” episodes are the ones who had HBO max.  We’ve all been on the 9 month delay since 2015.