There is no other reason to use the system People tags other than for face recognition. So, it is perfectly fine for you to just use your own hiearchy of keyword tags to identify the people in your photos.
I used to think that face recognition was a waste of time since I didn't see the point of looking at a gallery of faces (in the People tab). I was also very adept at selecting and tagging my photos with names of those I wanted to tag and thought I could tag my photos faster manually. However, over the years, the technology has improved in both speed and accuracy. I now believe that using FR makes the job of tagging more efficient. This past weekend, I took several hundred photos of holiday lights in a part at night. Interspersed among the photos were various members of my family. After a very fast media analysis of the photos, I was able to tag the 6 members of my family who attended the event with maybe a dozen mouse clicks. FR accuracy and completeness was at least 90% in dark conditions and even though our faces were masked in many of the photos.
If it turns out that you do have to tag 25,000 photos, I would highly recommend upgrading to Elements 2022 and using FR. In my experience, it will conduct the face recognition faster than Version 15. In addition the media analysis includes Smart Tags which does a fabulous job of automatic keyword tagging. These days, I don't feel a huge need to keyword tag my photos since the automatic function will likely allow me to find what I am looking for in an instant.