Yeah, the part of converting it to widescreen is stupid. That ain't happening. You can't just lope off the top and bottom from something shot in full frame.
Well, you wouldn't always do that. Sometimes you'd cut only the top, or only the bottom, or a combination of the two. Whatever works for the scene.
That being said: Many shows were intentionally filmed 'loose' such that the total amount of area actually captured on film could be hard matted for 4:3 *or* 16:9. That's basically what they do with IMAX movies. The native ratio of IMAX is about 1.4:1; when transferring an IMAX film to 4:3, they cut off part of the sides, whereas a widescreen version (such as Blu-Ray) has the top and bottom trimmed. No one has ever seen an IMAX film in its native ratio outside of an actual IMAX theater...