Is it really a 'dilemma' though? Basically, a project can set the version numbers how they want. They don't need to justify the change. So long as they and others can refer to each release by a simple and easily identifiable number or moniker, it really makes no difference if it's 5.0 or 4.22. In the end, the Linux kernel is such a big project that there's really no reason to single out any single or a set of changes as significant enough to warrant a version number bump; it's all arbitrary to start with.
It has value to certain people, sure. But given that it's mainly technically minded people who work with the kernel on a daily basis, and most people don't need to know their kernel version number outside of limited circumstances.
I would say for the majority of Linux users, it's the OS version that's more important; that is, getting help with your installation of Ubuntu, it's more useful to know that you're running 18.10 rather than kernel version 4.18.
Yes, Chrome-style versioning has value. But is that value applicable to this scenario? I wouldn't say 'no', but I'm fairly comfortable saying "not necessarily". Nothing is universal, and no one solution solves every problem.
There have been plenty of Linux releases with triple digit patch series. I'm familiar with 3.18 reaching 131 and I know 3.0 and 3.2 got over a hundred each as well.
Also, by any reasonable definition, there is no meaningful difference between 4.20 or 420. You just put a period in there. The major number has no real significance.