Disclaimer: I think this is a very fun discussion, and I'm glad you made this post! Savings rates are very valuable for comparing your own personal growth, but it becomes kind of useless as a way to compare yourself to others, because of many factors Sol pointed out.
The one area where I have a really tough time figuring out how to quantify savings rate for me is roth vs traditional contributions.
For example, when I put a dollar into my Roth IRA, that's really damn powerful. It's like a superhero. None of that will be taxed, nor will any of the earnings. Plus any of the the principal can be taken out any time I want penalty free.
However, a dollar put into my 403 account is far less powerful. Not only will that money be taxed eventually, but so will the earnings on that dollar. And I can't access is unless I wait till I'm 59.5 or unless I convert it to a roth for a half decade.
So, it costs you a bit of savings rate bragging rights to get a dollar Roth'ed into superhero status (gotta pay taxes on it first), but it can be worth it.
Another area where I have a tough time quantifying my savings rate is my pension, because:
a) My contributions stay mine and earn interest, but I most likely will never get THAT money back, it will rather take the form of a monthly income. So, for example I currently could get a check from the state of Michigan for 80k right now, but my plan is to forego that option to get a monthly income later that I will value more.
b) My employer makes contributions on my behalf, but it only goes towards the pension once I retire, so I'd never get that as a lump sum.
How I reconcile that: Currently I just use the cash payout I could get if I were to quit and take the check when calculating my net worth. However, when I retire I'm going to drop that. At that point I'll say that my net worth is "x" in the stache + "y" in home value + "z" in annual pension income.
So, savings rate is not a black and white thing, but I still think it's really valuable because you can measure it however you like, and use that as a way to challenge yourself.