Yes, groups have full right to come or to leave, no problem. And translating manga costs money so nothing to say about there Patreon pages as well.
But have they thought this from readers point of view?
For example me, I work so I can read manga while getting to work, getting from work or while no one is annoying me at work. I read mostly from phone as its easier for me.
About many of groups that are leaving I found from MD, and now if i want to read there translated manga, I will have to go to there sites and search there. I would not be problem if I was reading only about 5 mangas so checking daily would not take so long, but personally I am reading 174 titles and I spend about 3 - 4 hours daily here at MD. And not all groups have "normal" readable sites as well.
Not saying anything bad about groups that just MY personal view. As i will have to drop lot those mangas they are translating as i do not have time to check every translators site daily.
Best of luck to all groups that decide to leave. Best of luck.