You don't know how fast the group leader is... and it is not all about speed. Enjoy the ride. And the leader certainly would be working to ride at the pace of the group.
Our local riding group lists: 10-12 MPH, 13-15 MPH, 16+ MPH. And, some rides are flatish, while others head for the hills.
I presume all the ride leaders are volunteers, and they like to offer a variety to the public and group members.
I don't see Drop vs No-Drop listed, but that is also a distinction that many groups make.
If you have a No-Drop ride, it doesn't really matter if a person falls behind a bit. The group will stop at the next major intersection and regroup.
So, if you joined the slowest ride, then don't complain about speed.
If you were riding your Hybrid following 30 feet behind a 25MPH paceline up and down hills and along valleys, then kudos to you!!!