It was really cool! The ease of getting started was definitely one of the selling points for the “home computers” of that era (GW-BASIC ran on IBM compatible PCs instead, but the appeal of BASIC was the same). Brevity was an important feature since a lot of people obtained programs by typing them over from a magazine or recording them from the radio. And of course, there was no such thing as auto-complete (let alone AI generation).
That being said, SDL isn't actually that bad either. A minimal example is about 40 lines of code [1], not counting comments and blank lines, but including lines with just a curly brace which you could easily remove if you were concerned about size. A slightly more serious implementation of Snake runs about 345 lines of code [2].
And to be fair, DONKEY.BAS is also cheating slightly on the line metric by stuffing lines full of statements, like for example:
A$=INKEY$:IF A$=CHR$(27) THEN 1298 ELSE POKE 106,0:IF LEN(A$)>0 THEN LINE (CX,CY)-(CX+28,CY+44),0,BF:CX=252-CX:PUT (CX,CY),CAR%,PRESET:SOUND 200,1
SDL is incredibly terrible based on that example - I imagine it would be about five lines of qbasic?
Yeah for the rendering a smooth set of RGB shifting colors using SIN you could do it in a few lines of QBASIC.
The only thing is that since the SDL example uses a 640x480 resolution, which corresponds to SCREEN 12, and in QBASIC it only gives you access to 16 indexed colors at once.
So you have to "cheat" by redefining a single entry (like index 1) throughout the loop with calculated RGB using the PALETTE command. It's basically the equivalent of palette color cycling used in some older games.