I know that if my MIL (passed away now, and a wonderful woman) had had a DD she would have been called Karen, and had she got her way all her children would have names that began with 'K'.
I don't get it, and therefore HAVE to say YANBU to 'not get it' but on the other hand, because my MIL was such a wonderful woman, I can't get irritated or belittling about the choice. If that makes sense?
I don't think you're an old fart because it's not a new 'thang' (down wit the kidz me) it's simply something you don't really get. I don't get it because I don't understand why I would ever wish to give my children initials that are the same as each other.
YABU to think you have to understand it. I don't understand why, when I wear turquoise I feel the need to wear turquoise eyeliner, jewellery and underwear... you don't need to understand it, you just need to accept that it happens, it's harmless and people have their own reasons.
I think if you/I/we can accept we don't get it and it doesn't matter, then that's the only outcome that is 'good' and right and just!
It doesn't MATTER what the reason is, although from a nosey/interested perspective I can see why you'd ask so I come back round to YANBU.