I’m not even old. I’m 24 years old. I vividly remember in the early 2010s when I was a kid, online dating sites were made fun of as being for old people / socially inept people (losers) only; by teens and young adults. Fast forward to now and online dating apps / sites have become the main way to meet people throughout all demographics. What triggered this shift? Never used a dating app / site as the concept has always turned me off.
Probably Corona. Social avoidance in teens led to lack of social skills and lack of offline dating opportunities. Shift to online is a logical consequence.
Shift happened well before 2019/2020.