Why not? I have loads of different accounts from gaming services with friend lists and chat: Steam, Epic Games Store, Blizzard's Batte.net, etc. It would be nice if those were interoperable.
If you open the text and look at section 2 of bill S.2658, you will see the definition of "Large Communications Platform Providers":
(7) LARGE COMMUNICATIONS PLATFORM.—The term “large communications platform” means a product or service provided by a communications provider that—
(A) generates income, directly or indirectly, from the collection, processing, sale, or sharing of user data; and
(B) has more than 100,000,000 monthly active users in the United States.