To be fair to those users, Debian Buster did break systemd-shim, so co-existence of both inits in the same installation was looking uncertain for MX19, if not for the person who stepped up to look into fixing the shim package for Buster.
So for those users who like MX but need systemd for some reason, they might have had to find another distro if MX decided to stick with antiX base and go full on sysV with no systemd.
Or if they wanted MX to stay with sysV as default, they might have left -- possibly to antiX -- if MX went completely systemd.
I think in their own way, both antiX and MX offer an
out-of-the-box alternative (I'm sure Head on a Stick will be by soon to explain that if you knew what you were doing, you could choose from a range of inits besides systemd in Debian proper,

) to systemd-as-default in Debian-land.