The main problem is once the database is written, it's often out of date. This is mostly due to two issues. First, not all repeaters are coordinated (the most likely method of getting accurate information would be from the frequency coordinators). Second, repeaters change all the time. They go up. They go quiet. They change settings (mostly PL tone settings). Etc. etc. etc.
There are also lots of repeaters changing recently due to the very low cost of those Yaesu Fusion repeaters. While many are set to auto-detect analog/digital operation, many others are set for digital only operation. Without a matching Yaesu digital radio, you may be cut out on those.
At least most ham repeaters use a standard offset so the radios can easily guess what it is with 99+% accuracy. Also, most ham radios can search for the correct PL tone so with a little effort, that can be set correctly as well.
A simple scan can locate an active repeater and with the proper settings you'll know several things. First, the frequency. Second (and possibly the most important) that that frequency has folks listening and talking on it at the time. Third, the PL tone being sent by the repeater (this may not be 100% correct but only a relatively few have different input and output tones configured). Worst case, you may need to wait for the repeater to ID, which often includes what tone(s) are needed. This will generally be more useful than an outdated database that has a dozen repeaters listed for the area but only one (that nobody uses) that still is configured like the database indicates.