freebsd didn't have the hardware support base that linux did and suffered a huge delay in rearchitecture when x86 smp hardware became widely available. (only one cpu could be in the kernel at a time, the "bkl", was a major impediment in the early 00s). freebsd had better resource scheduling at the time and a beloved networking stack, but linux caught up with cgroups etc. i think linux was also just a trendy vanguard of sorts as the world learned of open source software by and of the internet.