You didn't read/hear about the Intel/ARM/AMD processor, did you?
If not: Apple Confirms 'Meltdown' and 'Spectre' Vulnerabilities Impact All Macs and iOS Devices, Some Fixes Already Released
Good point. Seeing as they were aware of these vulnerabilities back when 11.2.5 beta 1 was released in 2017, they probably knew to leave .2, .3 and .4 to address vulnerabilities and other security related fixes.