That's definitely not true, or at least not my experience. Everyone I ask out to join me for various activities, has an excuse, usually busy or other plans with someone else, and they never follow up for a rain check.
People over 30, even single/child-free, seem to be very busy with their established routines, hobbies, and narrow circle of long term friends, that they just aren't open to new people anymore or at least making time for them, no matter how cool or sociable you are.
Seems like time is the main cuprit, or lack thereof. If you already have things to do and enough friends that occupy all your free time, or barley have enough time to meet the friends you already have, then when are you gonna meet new people?
Making friends is a two way street. You could be the coolest, funniest, most sociable guy ever, but if everyone you meet already had enough friends or feels they don't need you in their life then ....
The only shot to make this easy for you is meeting other loners.