If you "worked on a team that did multi-OS TCP/IP optimization", then you should know that there is no one size fits all solution that is quantitatively better

If you "worked on a team that did multi-OS TCP/IP optimization", then you should know that there is no one size fits all solution that is quantitatively better for everyone. Not implementing cubic in FreeBSD when there was a bug in the only implementation of it in the world could have been an advantage in certain situations, including Facebook's. There seems to be a hubris by many Linux users that Linux is the best solution in the world for everything and it is not. There is always someone who does something better. Maybe not in everything, but the same applies to Linux. No matter how good it becomes, it is not the best in everything. Networking is a broad topic. I don't think Linux is the best in every area of networking. I am not even sure if it is the best in many of them, given that many platforms do things very well and at some point, it is hard to be better.