File system based databases like Microsoft Access, FoxPro, FileMaker all have built in vulnerabilities to data loss. File corruption, hard drive failure, user errors all leave you with no alternative but to restore your last backup of the files. When was your last backup? An hour ago? A day ago? A week ago? More? Can you afford to do all that work over again, if you can even reproduce the data to input?
Web based databases using real database servers are not susceptible to these types of data losses, and if properly configured, can be restored to any point in time. That is, they are continuously backed up. Add off-site storage of database backups and you are virtually assured of your data's availabilty.