The author is interested in PL design, and thinks that while C++ style object implementations are great at offering compatibility with certain systems or interfaces, other approaches allow for far nicer semantics in a greenfield programming language.

For example, fat pointers make it possible to implement interfaces for existing types. I have experienced that as game-changing in Haskell, Go, Rust.

I also disagree that any memory usage can be handwaved as “no longer relevant today”. Electron, or garbage collection: perhaps. But object size affects cache pressure, and cache utilization is critical to performance. C++ is typically good at keeping objects small, except when it comes to multiple inheritance.