The first Google search hit for the UK variant of the law[1] says this:

  This includes a range of websites, apps and other services, including social media services, consumer file cloud storage and sharing sites, video-sharing platforms, online forums, dating services, and online instant messaging services. 

[1] https://www.gov.uk/government/publications/online-safety-act...

Depends on what you consider "practically its entire existence": the same could be said of Google Search if we are looking at how long they did not compared to the rest of the time, but I distinctly remember the period when they did not and when I recommended them to my entire social circle as The Search Engine (compared to Yahoo, Altavista, MSN or whatever else was there at the time) or The Social Network (compared to MySpace, I can't remember anything else that was comparable).