That sounds about right. (Just to clarify, what I was referring to with "did not exist at the time" was specifically Self's JIT and its new techniques.)
With regards to performance, Craig Chambers's thesis on the Just-In-Time compiler for Self proves pretty definitively that a language as (or more) flexible as Smalltalk can be very performant without losing any dynamic properties. It certainly isn't an easy compiler/runtime to recreate for any given language, but it does exist.
It didn't exist at the time you're referring to however, so in that context the point does stand, mostly. I believe there was some form of flexible compiled optimization for Smalltalk (since Chambers's thesis references it as prior work) but I forget when that was and how commonly used it was.
DOOM was definitely made with DOS in mind, but it also ran on NeXT from the beginning. It's pretty portable actually. Since you cited Fabien Sanglard, I guess I should mention that his book about DOOM's source code (Game Engine Black Book: DOOM) explains how the portability stuff (as well as almost everything else) worked in great detail.
The Build engine's source code isn't enough to port any game running on it, since Build was made as a library (I believe most developers using Build in the 90s didn't have access to the source code).
Also, wasn't there an official Blood port by Nightdive Studios?
It's wonderful when I have to show my ID before I can watch a video of the funny man saying fuck (I'm not kidding, that's sometimes but usually not enough to get it automatically age-restricted).
Why not? That's how proper English text is written. Of course there are many programs that can't handle it properly (or handles it inconveniently) so in practice it might be problematic at times, but otherwise I see nothing wrong with it.