I leave windows defender on 100% of the time on my personal laptop. It's totally benign in my experience and doesn't have any obvious performance impact that I can see.
I would never tell anyone to turn off windows defender. I have told people to uninstall ageing AVG/avast/Norton et Al installs that have not had definition updates in months/years and really do seem to impact day to day use of the computer.
My view is leave the virus checker that was built by the people who made windows and is built directly into windows there to do the job that the people who built the damn thing designed it to do :)
Linux is a wasteland of terrible security practices that sysadmins excuse as "acceptable" for their own workstations and servers because they think that locking down SSH is sufficient defense against e.g. malicious infections or "curl | bash".
I'm sorry that Defender has harmed you, but that's no excuse to recommend others disable automated Defender scans on some sort of schedule.
It has little to do with the functions of Windows Defender. It was a special purpose function removing one very particular file from a specific location. It was not scanning your whole system, or downloads, for malware signatures.
When you say MacOS includes software that is "almost a carbon copy of Windows Defender," are you talking about something else? I am not aware of anything that comes with MacOS that has similar features to Windows Defender.
https://www.osnews.com/story/22059/snow-leopard-to-include-a...
Stop telling people to turn off Windows Defender.
Today, we consider C and C++ to be inherently unsafe, because nobody ever does the things you need to do to make them safe. It's time we said the same about operating systems. "Oh, just don't run anything sketchy off the web!" Except your user base won't do that.
In 2019, any OS that does not come with strong antimalware protection is inherently unsafe at any speed.
Yes, this means Windows is safer than Linux. Don't @ me.
If nothing else (and there is), mac and linux need anti-malware to make sure they will never spread windows malware. E.g. in mails, or uploaded files.