They are always hailed as a failing, but its not. ss13 wouldn't exist if byond was a competent programming language.
Half the features wouldn't get coded if class members had visibility/security levels (public/private), or had to be well written interface defined frameworks, or if types were enforced or required to be specified.
Lacking all of the fluff of modern programming languages allowed it to appeal to a wider base of contributors, a fair amount who got their start in programming by contributing to ss13.
Non-visualized programming languages also have issues that make game dev hard, that byond can sidestep. byond uses a single-thread:multiple-stacks framework that treats soft blocks (sleep, network/file io, client involved commands) specially and allows you to detach your call stack at an arbitrary point when a softblock happens allowing for easier programming of performant code.
So if i have code for airlocks to start the close animation, sleep for the duration of the close animation, then mark the airlock as dense and the tile its on as an airblocker, I can easily make code to handle closing all doors in a list of doors without making each wait thru the animation of the close block the caller, while still allowing for the blocking of the caller when thats what i want.
The curse is real, but its not insurmountable.