Any reason for not doing backdrill under BGA

[buenos]

Is there any reason for not doing/allowing backdrill under BGA?
Maybe something that violates the soldering/assembly process?
I mean backdrill from the bottom, for 10G signals.

 

[anilrock87]

https://www.freelists.org/post/si-list/Backdrill-under-BGA,9

 

[marce]

For that speed I would use HDI PCB design, you get more control of the 10G signals and it would probably be cheaper, less layers etc.