I've never understood people's fascination with replacing glibc. There's almost never anything to gain- and glibc has the advantage of being really, really well tested.

"I've never understood people's fascination about SpaceX. There's almost nothing to gain- and Russian Proton has the advantage of being really, really well tested."

On a serious note: the primary disadvantage of glibc is that it's really, really hard to change (and build times are slow). While it's already here, sometimes you want to port it to a new platform or a new ABI, and the adventure begins.

As someone who tried to port code in the early days of Bionic, I am filled with grumbles.

And glibc hasn't been slow for a year or two, since they defenestrated Ulrich Drepper.