Program setting itself as default for MS Office files without asking

I found a free office suite in the Apple App Store, WPS Office. So, it being free, I downloaded it. I also have SoftMaker Free Office and LibreOffice installed. I do not have MS Office but need to open Word or Excel files on occasion.

After installing WPS Office, it made itself the default program to open MS Office files, taking over from LibreOffice. It didn’t even ask if I wanted this to happen. So I contacted the WPSO support team and was told this:

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Sorry for that we cannot change it, because it depends on Apple system.

Apple system makes the latest downloaded program as default program.

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Is this true, that the latest program becomes the default because of the design/programming of macOS?

Yes, I know how to change the defaults and have done so, but would this mean that if I download another word processor I would have to change it again? Not a big deal, just seems to me to be an unusual thing for Apple to do.

I am using Catalina on an MBAir, but I don't think this question is limited to my case.