Of course it did.

For two reasons.

First - if anyone complains they can always say there exists a bypass, no matter how idiotically unworkable and annoying the process might be.

Another aspect is that devs will probably want to test their apps easily and quickly - App stores are notorious for updates taking a few days to be approved. Even for Google, full-on lockdown might seem overkill. They don't want to bother with speeding up their update approval process so devs can push test builds through the Ecosystem. Giving some route towards sideloading is a much saner solution.