It is a little dangerous to do in case you experience a crash or a power failure, but you can get a lot more bang for the buck from your server hardware if you have a decent amount of memory by tuning your different system components to keep more data in memory and write to disk less often. This can be done with sysctl.conf and dirty writes, or with php or MySQL using more working memory and not writing to disk as often.

It was particularly required when I was still using a spinning drive, since random io was a show stopper. Even using a decent sata SSD it can be beneficial however, letting the system choose to write at more opportune moments instead of doing it in the middle of read ops.