(a) LE keys don't have to be all powerful. It can require actions from other parties such as the company that is running the chat or a judge. It can limit the s

(a) LE keys don't have to be all powerful. It can require actions from other parties such as the company that is running the chat or a judge. It can limit the scope of who or what messages can be decrypted. (b) Perfect is the enemy of good. Smaller services won't have the same utility and network effects of large ones.