I've worked remotely for most of my career, both as an IC and an EM, and across the board if it took someone 4 hours to respond to a crisis during their normal working hours it would be viewed as a serious failing. Of course if your company chooses to let remote employees get away with murder the end result will be remote employees getting away with murder! If you needed someone who was working in office and they were missing for four hours you obviously wouldn't just accept that as the way things are.

Sure, partially it's a failing of management. But all the management is WFH and unresponsive as well. So it's easier for me to just ignore whatever team I'm in and work with the people sitting around so I can actually get stuff done.

Fair play, I imagine I'd do the same in your situation, sorry to hear your management is asleep at the wheel -- I'm a big advocate of WFH but it does require people (especially managers) to change how they work and communicate in order to work successfully.

WFH is a two way street. Communication is key. It doesn't necessarily have to be synchronous, but most WFH companies are built around synchronous Slack communications. But whether synchronous or asynchronous, communication has to be thorough and responsive.

How do you coworkers expect to get a promotion and/or survive the next round of layoffs? Responding on Slack is the new "butts in seats" for bad managers, and good managers notice good communication.

If you're the type of guy that is always helping out your colleagues, that's behaviour that was often counter-productive. It too often wasn't noticed, and didn't show up appropriately on your 6 month review. But when you do it on Slack, it's noticed, or at least is more likely to be.