Database file ..._log has a max file size set to x MB. If it runs out of space, the database will stop working
When someone does a BEGIN TRAN, inserts a row, locks their computer, and goes home for the weekend, your log file will grow and grow and grow.

That would be a Bad Thing™.

Rather than facing an outage, you're better off letting the log file grow, and using your monitoring tool to get alerts that there's a problem.