Assertiveness isn't some superpower that only extroverts have. You can't expect things to happen for you, you need to stand up for yourself and explain why you're worth more to your company than they are paying you.
It's also a skill that is not directly proportional to your value in a company. Effectively, this just moves the problem of compensating fairly somewhere else, without actually solving it.
Especially for people that do great work but maybe are a little less extraverted.
If you can't perfectly negotiate and influence multiple people you are practically f..ed.
Glad not to have such types of so called managers trying to tell me what's good for me.