I think it is a meaningless figure also. Not only should it be no significance to a retirement plan, but a home's value can fluctuate MUCH. I guess that is my perspective from a HCOLA perspective.
Likewise, I find that figure rather useless. I think it is more important that when you buy a house that it is in your range of affordability.
I understand you are trying to decide how much to spend on a house now. Which is probably a better question - how much of your net worth should you spend on a house, as you near retirement?
But figuring out where your house should fit in retirement (particularly if you bought in your 20s/30s) seems a rather useless exercise.
I think my parent's house is about 50% of their net worth, but they paid off their "starter home" ages ago and have the financial freedom to cash in their house and move just about anywhere else (would be cheaper). Their retirement savings is very fine. Likewise, we bought our home in our early 20s. We felt it was very affordable. I could care less what percentage of our net worth it will be in 40 years. It just doesn't matter.
I'd rather take a house that appreciated 1000% in 20 years, like our parents.
It probably depends largely where you live too. What that ratio ends up as. As my example shows. We have a lot of relatives in Kansas and NC. I wouldn't expect their homes to be more than 10% of their net worth (if that). Some of their cars cost more than their homes.