It's still not being destroyed. Even splitting water into it's component parts rarely destroys it for long, since the subsequent hydrogen is usually burned, creating more water.
You are correct that it does not literally destroy it, but it's also true that there is a finite water supply in that system, and that number is dropping.
When it ends up in the environment and eventually the ocean, fresh water is destroyed. Period. It is no longer fresh water. You can reconstitute it at great expense, manufacture it practically.
When it's pulled from deep, ancient reservoirs that get replenished very slowly it's slowly destroying the reservoir. Given the time-scales involved, where tens of thousands of years or more are required to re-fill these, it's effectively permanent destruction.
Your argument is extremely misleading. It's like saying gasoline isn't destroyed by cars because you can always reverse the process.
The water as element (H2O) is not being destroyed, but the water source (usable groundwater resources) may actually be destroyed or at least depleted so that recovery takes a very long time.
Good.
Then we'll move to sources that are super-expensive right now (desalination, etc), and we can finally have a discussion about the agriculture situation and whether it makes sense to irrigate a desert just because you can.