Again this is stuff you're just inventing because you don't know better.

> Boiling the water first avoided many spoilation problems that, today, we know how to prevent through other means.

You have this backwards. Boiling or near-boiling the water is what's nearly universal now. It was much less common in the past.

> Prior to modern knowledge, beer recipies were based on trial and error.

Correct. However, all beer is mashed. You don't get beer without it. That's a one-hour 65C pasteurization at the very least. As far as we know, all European beer from the stone age until now was made this way. So you can take this part as ordained by the gods of chemistry. So no matter what you do about the water initially, the whole thing will be pasteurized afterwards.

There are still people today brewing traditional beer from recipes based on trial and error, with zero input from modern science. Some of them start with a mix of cold water and malts that they then heat in the kettle. Here's an example of me visiting and brewing with a guy who does exactly that https://www.garshol.priv.no/blog/409.html

If you want I can make you a map of where in Scandinavia and the Baltics people used this method the last 100-200 years. Before that people often didn't have kettles, and so (as far as we know) the water was not heated before brewing (long story exactly why we think so).