Definitely not true and likely has never been true. Many of the most attractive women I know are active on online dating. People join online dating for various reasons. One is to expand your dating pool. If you've burned through a lot of your social network (or you don't want to poison it) then online dating is a great way to expand your horizon.

From what I gather, it really only amplifies what you experience in real life already. If a significant amount of people show interest in you from a very early stage - you will have no problems with online dating. If you require any kind of barrier to get interest, I wouldn't bother unless you have the incredible ability to not evaluate your self-worth from the app regardless of what happens.