CCleaner is not the best system junk files and registry cleaning tool, but on balance it has not bad cleaning effect and less negative impacts to system stability. So it is a matter of course that CCleaner has become one of the must-have tools for PC users.
As one system trash/privacy cleaning tool, on Windows, CCleaner has already unified almost the whole PC world for long. Especially when it could work with Winapp2.ini, BleachBit just can't compete with it. Therefore, BleachBit's main market is still in the numerous Linux distributions, and in fact, it does very well.