I may have met my first husband when he bumped into me repeatedly at a dance club (because those things are common at 20), but I met my second husband on OkCupid. I also met the guy I am dating now on OKCupid (albeit after seeing him on fetlife and recognizing him from my matches, who knows if that would have happened if I hadn't taken the effort to reach out). My husband generally finds dates through OKCupid because the chance he is going to run into some random person other that at work whom he can become enamoured with is small, let alone somebody who is open to poly (and we don't date people who are think they will just "give an open relationship a shot")
Meeting people randomly is great, but that is if you are generally outgoing. With website tools that help you find and learn about people you might not ever run into, what is wrong with taking advantage? Besides, love/lust at first sight is really uncommon for me (once every few years), so how many other people might you click with that you didn't get a chance to because you knew nothing about them during a chance encounter and weren't struck by chemistry that moment? My husband is very social, I am somewhat introverted, so some of the things like big poly events aren't as great for me to go to at least.
You can always use them as an opportunity to meet like-minded friends, hobby partners, adventure partners. You don't HAVE to be searching for relationships, which is what is so great.
Happiness will never come to those who fail to appreciate what they already have.