I agree 100%. ESH.
Its okay if this niche thing is how this person found friends. Maybe she is introverted or otherwise has a hard time connecting with people. But that doesnt excuse her behavior. She can't help if she feels insecure, but she can help the way she treats the group and handles her insecurities. Her insecurity isn't the groups to manage. Her comments are condescending and just generally "off" given the tone of the group and how they hang out.
The group, and OP, are assholes for letting it boil over to this point where everyone was just silently irritated at this woman until it hit a breaking point and someone snapped at her. Its not hard to pull this person aside and gently let her know her comments are uncomfortable or unwanted. She may not realize the way shes coming off or that she's making those kind of comments so excessively. Had some one said "hey, wed appreciate it if you stopped bringing age into every thing" she could have had a chance to stop and make things better or better connect with everyone.
These types of problems wouldn't happen as often if everyone just communicated their frustrations and expectations.