Comment by AnIdiotOnTheNet

Defender is probably the least offensive AV in existence, sadly.

Frankly I think the entire concept of AV is bankrupt as it always causes many more problems than it is worth. Both false positives and false negatives are common. You shouldn't be afraid of running without Defender because, like all AV, it isn't very good at catching real threats anyway. If you really want to feel safe there are much better ways of doing that, like running untrusted programs in sandboxes or VMs, or using Software Restriction Policies to whitelist what can and cannot run. I haven't played with it at all, but there's even Controlled Folder Access to limit FS rights by application, which isn't a terrible idea given the era of crypto-ransomware.