Writable typed constants are much older than Object Pascal.
They serve - amongst other - a distinct purpose: maintaining state within the context of a procedure or function.
example:
program state;
{$mode iso} (* ISO mode has no object extensions and $J+ is the default. *)
function HowManyTimesDidYouCallMe:integer;
const T: integer = 0;
begin
inc(T);
HowManyTimesDidYouCallMe := T;
end;
var i:integer;
begin
for i := 0 to 9 do writeln(HowManyTimesDidYouCallMe);
end.
So it is actually *very* usefull in a non-object oriented pascal program.
It is just that not many younger programmers appreciate its power.
The state of T is bound by its function (although in the background it is still global, no other procedure or function can access it)
Think of it as a precursor to object extensions.