It's still the case that environments should be as close as possible. It's easier to achieve now because the number of environments have shrunk significantly.

It's still the case that environments should be as close as possible. It's easier to achieve now because the number of environments have shrunk significantly. Nowadays you will be running on a CentOS/Debian server or a Windows desktop, on an AMD64 compatible CPU. Not so long ago, there were tens of Unix and Linux variants with significant differences. It was impossible to support half of them.