Even if the number of software engineers is in fact overstated, that is still a lot of testers, even if you did use a 1:5 or 1:6 ratio. Because on one end, you will have 1:8 as a ratio, and on the other had, it will be better, and that still gives me at least 5 million testers, consider that around 1/4 of them do speak English normally, yeah, a lot of missing people.
My guess is people are busy in their day jobs, or/and do not get much from communities. I’m primarily an embedded software tester, and that means very little interaction of value to me because I’m in the minority. But I still learn loads from the community chaps about heuristics and and I get challenged to grow. You cannot really put a price on injecting life into your career.