Could you ever imagine a very big company losing important data because of incomplete backups or no backups at all ? If you think that large companies, that earn millions of dollars, backup their data daily or even hourly, then you are wrong. The reality is sad. A quite large portion of those high caliber corporations don’t even create backups and some of them that do, do not do it the right way.
The internet has always been about the information. Millions of people literally write billions of words of text everyday online and several others read them. This whole model is solely based on databases and database programming, which is actually the practice of storing information and retrieving it in an easy manner.
Running a server with Apache2, mySQL, cron and more can really be a RAM intensive procedure. If you are running multiple virtual websites, there could be a chance that your RAM is just not enough. Therefore, there is the need to decrease the RAM usage somehow.