Size likely has nothing to do with it, while reliability is a much bigger concern.
If your business uses said tool for all client work, and it's hosted on a single server (be it physical or a VM), that is a SPoF. Any downtime and your business grinds to a halt because none of your project or customer information is accessible to anyone.
It feels like you have to be a very big business for this to be a problem that is worth the extra engineering effort vs a single instance with an SQLite file that you backup externally with a cron job
Most stick trading systems and even many banking systems have availability like 40%, going offline outside business hours. But during these business hours they are 99.999999 available.
Usually operation without trouble is operation with plenty of resources to spare, and in absence if critical bugs.
If your business uses said tool for all client work, and it's hosted on a single server (be it physical or a VM), that is a SPoF. Any downtime and your business grinds to a halt because none of your project or customer information is accessible to anyone.