because we use NextCloud... 😁
ehm...
...jokes aside...
We (and many others) chose NextCloud because we like it better.
Others (I don't know how many, but certainly not a few) will probably choose OwnCloud because they have different tastes and prefer it.
Choices.
Gabriele Maoret - Head of SysAdmins and CISO at SERSIS
Currently manages 6 SmarterMail installations (1 in the cloud for SERSIS which provides services to a few hundred third-party email domains + 5 on-premise for customers who prefer to have their mail server in-house)