Prune old backups and

1. dbbackup.sh already handles older backups based on set threshold days
2. for downloads, clearing them just hides the problem in that if you do not have enough space in /svr-setup your future updates will fail as re-downloading the files still needs such disk space
3. for ccache, yes can clear but then recompiles still will re-grow cache size so still need that much disk space to function and compile via source. So again hides the problem in you need more disk space for these days or down the road, you will have problems. Hence, raising the min and recommended disk space requirements.
4. nginx backup routine can be cleared but serves a purpose, on the forums have members who accidentally deleted their ssl certificate for their site. They found a copy of their ssl certificates in their /usr/local/nginxbackup directory saving their bacon. So how far back to delete if user needs to obtain a backup of their config file ????

example of masked problem

imagine if your only had 2GB free disk space, and /svr-setup occupied 1.8GB and ccache occupied 1.1GB, you clear those 2 and have 1.1+1.8=2.9GB extra disk space so now have 4.9GB free space. A user sees they have 4.9GB free and starts uploading other sites and files to their nginx vhost i.e. 4GB of files so they have 0.9GB free disk space

but then they go to update nginx and php and redownload files to /svr-setup and they run out of disk space.