I use PM Plus from both my desktop and laptop and have to 'disconnect' or repair the catalogs each time I connect to them when switching my devices.
An option to select a MySQL or PostgreSQL database as backend would solve the multiple computer issue. I use a NAS with 10GB ethernet and a 10GB ethernet connection for my desktop and laptop and have no speed issues with PM Plus or CaptureOne.
NAS devices like Synology come with installable software like MySQL/MariaDB or Docker (which allows you to run various application servers with ease). I feel that customers who need concurrent access from multiple computers to their catalogs either have an IT person or know/hire an IT person to support their IT infrastructure and have the appropiate infrastructure in place or can afford to pay for it.
An option to select SQLite, MySQL/MariaDB, PostgreSQL on a per catalog basis can solve the concurrent use or multiple computer issue imho.