Another point not mentioned by the author: A lot of us choose to use an alternative (eg: gitlab), because we prefer to use FLOSS software, rather than a proprietary SaSS.
GitLab CEO here, thanks for mentioning us. We love FLOSS and we're proud to host projects like https://git.gnu.io/explore/projects And we're working hard to make sure GitLab CI is very usable and easy to set up.