It doesn't use any system resources and it does populate the Restricted Sites list, plus the tracking cookie list, but each to his / her own.
Good Question....I used to use it until quite recently.I removed it because of a few reasons As you eluded to above...I have an adblocker (uBlock Origin) that blocks the same things as S-B I use Chrome (and I have disabled IE) so I no longer need the "Prevent IE Homepage from being changed" function. I have locked my "Host File" with my Firewall (ZoneAlarm) so I do not need the function in S-B Despite my having removed it,I do not have a bad word to say about Spyware Blaster,as I was a happy user of it for over a year... If you do not have another security soft that will perform the above 3 functions then I would say keep S-B... If you do have these functions covered then you could do without it if you wanted to.. But I agree with @Krusty13 ..."each to his / her own"
When software becomes obsolete, it is usually abandoned, these guys just keep it on. Their official forum is Wilders. It still offers some basic protection to IE and IE based browsers, but since IE is basically dead, well needless to say more?!