I've got etrecheck, and in last using it, it found the only major issue is "heavy CPU usage", and minor ones being, again "heavy CPU usage" (and this is without using any high memory required media-oriented apps) by some apps, and some apps that "may not work in the future". I do have a few of the "useless apps" you mention, however, your opinion is not one shared by a great many tech people. They don't have 100% faith in Apple's OS to secure our machines from all interference from hackers, viruses, etc. I would think if any of these 3rd party optimizers or anti-virus scanners were that detrimental to our machines, that this would be a more widespread belief, and everyone would be on the same page, in terms of warning users to not use any of them. I have Memory Clean 3, and it seems to effectively, and quickly, free up a good bit of RAM, when things begin slowing down. And Onyx has been used for many years to help clear caches, without anything going awry, etc.
If removing these programs were the magic bullet to solving all the issues people have with their Macs, why wouldn't everyone just do it? I've been hearing the same dire warnings for many years, no matter what OS was current at the time, yet they still live on, so one perspective on this can't be right, unless the other is wrong. Why would this warning not be more widespread, if these apps are so very disruptive to the functioning of the OS?
Also, as to un-installers, I'm not sure what else to use, if the developers don't offer one for their apps, and I'm not sure we can count on simply trashing an app, to remove all it's files associated with it.
I'm honestly wondering, since this recommendation has been a common one on this site, but not so much on any of the many other forums & techie websites.
