Which big US social media company operates without some form of involvement with the ADL?

This isn't a conspiracy, the ADL openly admits and is proud of their involvement in censorship.

Here they are bragging about their role in youtube censorship:

https://www.adl.org/resources/press-release/adl-applauds-goo...

Google search results censorship:

https://www.adl.org/resources/news/can-google-search-be-used...

X may be the one exception, though I note that the "advertiser boycott" was ended when Musk made trips to Israel, was photographed next Netanyahu's atrocity propaganda prop pieces, next to Ben Shapiro, etc.

Musk first posted an antisemitic tweet, which caused a minor scandal. Then, to atone for that, he traveled to Israel, met with Netanyahu, and had Twitter begin boosting pro-Israeli content.

Musk went from antisemite to Israel fan in the course of just a few days. This actually isn't so surprising, though. There are many people who are both antisemitic and pro-Israel (see basically every far-right party in Europe, for example).