I don't think anyone is saying that your explanation is wrong. I've noticed that the location arrow comes on a lot. It's basically the only thing that pops up multiple times in an hour, at least for me. Now whether it causes discernible battery drain is something I'd have to test.
I don't think the person who turned off location services and gained battery life is wrong to point the finger at location services draining his battery. If it's coming on multiple times in an hour, it's going to drain battery. It may be a minor amount, but it may not. If that's the only variable that is being switched off and all other things remain the same, I find the assumption that location services is causing the battery drain is valid.
The thing is... system location services doesn't pop up as it's own service in the Battery section of settings. So how would you really know if it's not draining battery? The answer is you don't because it isn't listed as something that is able to be shown in the first place. Every single app shows up in the Battery, yet system services does not. Unless you can tell me what category it falls under?
Here's a proposal for Apple developers. How about you guys add a user selectable query time for Find My to activate? Poll every hour? Let the user decide.