I think you're confusing two things here - the perspective of the capitalist / corporate system vs. your individual perspective as a worker.
Of course, the capitalist and corporate system is not your friend, but your employer, and it's designed to extract the maximum effort and time from you, to the owner's / shareholder's benefit.
From your worker's perspective, it is not good to communicate outside the work hours for your work-life balance.
However, from the perspective of your employer, the employee's dedication to the corporate system and a can-do attitude, are beneficial, and will reward it. Because it shows the dedication of the employee to sacrifice their own personal life interests in favor of the interests of the owners / shareholders. And yes, a can-do attitude and dedication includes everything, including quick work-related communication during personal hours.
And some people will always strive extra to impress the corporate system, for those extra rewards, including growth in the hierarchy.
You, from your worker's perspective, might resent it, but the corporate system will reward such behavior, whether you like it or not, over others who do not have the can-do attitude to show such dedication. This is the way the system is designed, and yes, it does raise expectations for everyone, because it's intended to do that to make everyone sacrifice more and work harder the benefit of corporate. And yes, it's designed to reward those people more who have lesser personal life outside, because they're dedicating their life to their employers. And you ranting and resenting it will not do anything.
The best you can hope to achieve in this system, is to start your own company someday, and have your employees communicate in their personal time for your benefit, while you sleep. And then reward such dedicated employees with growth and promotions, for working in their personal time towards increasing your wealth😄