Oh, there were always non-native English speakers around, its just that back then they were more likely to be rich/well educated and thus could converse on the English language Internet. (edit: They were also harder to count back then because they disproportionately used net cafes which were, for those under 25, pay per use computer labs open to the general public.) Only a few communities (Japan, China, etc.) largely did not and that was because they were big enough to really need that international component to talk about something as international as video games or cars. Now their population has grown but they no longer need to be able to speak English to converse on niche topics, so even the ones who are bilingual often choose not to. And, in the case of Chinese speakers, its a lot harder to get through the firewall now than it was back then (slipping onto the international versions of stuff like WoW or Runescape used to be a joke, now it seems legitimately hard unless you are doing it as a farming job-except the bots stole all that work.)
While social media is almost certainly inflating its numbers with scam stuff, I don't think 1.5 billion users total is off-base. Thats one in every 4/5 people. When you factor in that even third worlders have sat phones and talk on various chat platforms now that number isn't hard to believe at all. Its just that people are fraudulently reporting personal subscribers/ad sales. That stuff is being over-reported while the number of "viewers but not subscribers" or users of private chat services is being underestimated.