There is no straightforward answer to this question. Assuming that your infrastructure is "secure" because you deployed an EDR solution is wrong. It only gives you a false sense of security.
The reality is that security takes a lot of effort from everyone involved, and it starts by educating people. There is no quick bandaid solution to these problems, and, as with anything in IT, any approach has tradeoffs. In this case, and particularly after the recent events, it's evident that an EDR system is as much of a liability as it is an asset—perhaps even more so. You give away control of your systems to a 3rd party, and expect them to work flawlessly 100% of the time. The alarming thing is how much this particular vendor was trusted with critical parts of our civil infrastructure. It not only exposes us to operational failures due to negligence, but to attacks from actors who will seek to exploit that 3rd party.
It is not considered a silver bullet by the security team, rather a last-resort detection mechanism for suspicious behavior (for example if the network segmentation or access control fails, or someone managed to get foothold by other means). It also helps them identify which employees need more training as they keep downloading random executables from the web.
Any security certification has a section on regularly educating employees on the topic.
To your point, I agree that companies are attempting to bypass the hard work by deploying a tool and thinking they are done.
Personally, I don't know how to solve that problem.
But this will be the work of at least two human generations; our tools and work practices are woefully inadequate, so even if the pointy haired bosses (fearing imprisonment for gratuitous failure) and grasping, greedy investors fear (for the destruction of “hard earned” capital), it’s not going to be done in the snap of our fingers, not least because the people occupying technology industry - and this is an overgeneralisation, but I’m pretty angry so I’m going to let it stand - Just Don’t Care Enough.
If we cared, it would be nigh on impossible for my granny to get tricked to pop her Windows desktop by opening an attachment in her email client.
It wouldn’t be possible to sell (or buy!) cloud services for which we don’t get security data in real time and signal about what our vendor advises to do if worst comes to worst.
And on and on.