I met my late wife on Match.com in 2011 and we had a wonderful marriage. After she had passed away, I took some time to myself, but when I started dating again, I tried a variety of sites.
Hinge, bumble, tinder, and match all got me dates, but I eventually met my now girlfriend on match. We've been together over a year now and marriage is in the future at some point, we're just not in a rush.
It's worked for me twice now, so I think saying it's impossible isn't necessarily true. A lot depends on your location, interests, etc, but if you keep at it, you're likely to find someone eventually.
Perhaps post your online profiles, or portions of it, to some dating advice magazines and get some feedback. Without more information, we can't know why it's not working out for you in particular, but regardless best of luck out there!