Nobody ever said that. Memory and time are especially important for high-level languages, because they spend them in an uncontrollable way inside said languages.
For instance, the common approach of garbage collection is a huge topic in every high-level language. Because it takes a relatively simple operation (delete one item) and batches it up. So when it happens, it takes thousands or millions of times as long AND inevitably happens when you can least afford it.
You never stop thinking about memory (and cpu time) in any environment.
Erlang actually doesn't take the common approach, which is part of the reason it usually does "soft" real time pretty well. This is the first thing I found in Google when searching for a description of how it works:
For instance, the common approach of garbage collection is a huge topic in every high-level language. Because it takes a relatively simple operation (delete one item) and batches it up. So when it happens, it takes thousands or millions of times as long AND inevitably happens when you can least afford it.
You never stop thinking about memory (and cpu time) in any environment.