I just live with Windows Defender (heavily modified via GPO to disable sample submission and auto-remediation) these days as there is no such thing as a pure third-party antivirus product anymore. Avast (and basically all others) want to do things like install their own "safe" browser, MITM https connections by installing certificates in the root CA store, screw with firewall settings, etc which I absolutely do not want happening on my system.

All I really need is something that will hook into the filesystem layer and scan files as they are accessed/written/executed and gives me a clear UI that allows me to choose what happens if it detects something.

Some antiviruses are better than others, some are faster than others, prices are different (some are free), support is different.

See virustotal.com when sending a file, how many engines will find something, how many will miss, and how many will tell you that malware has been detected on a clean file.

Some of the third party EDRs do things than even the top tier Microsoft Defender XDR with Vulnerability Management can't do yet, and there is no "built-in" EDR for Linux.

Third party security tools have always been monkey patches for gaps in the OS. Eventually the OS gets the features that the third parties have, but then new threats create new requirements.

Whether you need it or not is a question for your threat model, but for me personally it's been years since I felt it was worth it on Windows. I still use a commercial EDR system on Linux due to the OSS solutions being quite lacking.

Part of the gap that still exists is cost. A cloud service that isn't constrained by your local resources can do more as far as password cracking or applying AI to the password protected document/container problem, but we're not at a point where they're going to apply that to every hotmail or gmail account for free.