That’s because water is necessary to life.

When doing risk analysis something that is required to keep people alive gets a few extra points towards being accessible for, hopefully, obvious reasons.

If even something that is necessary for life is controlled due to the danger it poses, you can imagine why people would seek to restrict dangerous things that people can live without.

Yes, and that’s why we don’t allow people to flood school, hospitals and homes with water. It is controlled and diverted.

Because religion can be and has been used to convince people to do terrible things. The fewer false beliefs people hold the fewer things can be used to manipulate them in this way.