Is number of FTP accounts limited?
Yes, it is limited.
After the creation of a new FTP account, the user with some UID is created in the system.
Type of the UID is `int32`.
According to the Linux official documentation, limit of the `int32` is equal to 2^32=4 294 967 296.
However, the limitation can be reached earlier - it depends on the file system, disk space, etc.