it locks out new browsers because acquiring CDMs can be a pain if you want to roll-your-own

https://hacks.mozilla.org/2014/05/reconciling-mozillas-missi...

ctrl+f for "What does this mean for downstream users of the Firefox code base?"

tl;dr you either need to run a mozilla-built sandbox with no modifications, or literally call up adobe and ask about being given a CDM for your own browser, which they might just scoff at