I disagree with this perspective. You should have multiple accounts but only if your organisation requires it for isolation or data protection reasons and only enough to perform the task.
Every other reason here is because you fucked up. You have poor architecture, poor tagging, poor VPC design, poor IAM policy and role modelling or don't know what you are doing to start with. And some of the stuff doesn't even make sense, particularly the point about EKS upgrades (I run three different versions of EKS in the same account).
There are many negative effects of multiple accounts including billing aggregation is very difficult, having to dig through several accounts worth of Cloudwatch logs, unexpected egress traffic costs and the overall complexity is much higher. If you have to switch to an org account and set up SSO you then have an administrative cost which is immense.
My favourite thing doing is spending 2 days opening support tickets in 10 different accounts to get a limit raised and then tracking the state of all the tickets and limit changes...