Online dating (which often gets mentioned in regards to this) gives people a sense of choice which they wouldn't necessarily get to such a degree when dating more "organically", thus it becomes easy to compare people against one another in a standardized manner and go for the ones you find to be the most appealing, which you wouldn't necessarily otherwise even meet in person. Similarly, being someone who's interesting and fun in person might also naturally catch others' attention - being the person with interesting stories, nice jokes and just someone who feels fun to be around and is confident.
If you are close to "average", this might also lead to you comparing yourself against others to a degree that is similar to the one found in social media, the effects of which on one's sense of self-worth aren't necessarily all that positive, unless they make you strive to improve yourself. People suggest that you really should socialize outside of online dating and not get too caught up in it - both to improve your social skills, gain actual friends and acquaintances, as well as become more comfortable with approaching people in the romantic context, should the opportunity present itself.
Personally, I've largely resigned myself from online dating and much of social media, though perhaps that's because of my introverted nature. Regardless, actually visiting other countries or even just participating in interest groups/events has been nice, as has been expanding my social circle - over the years, it has also lead to a relationship or two.