It really doesn't. I would argue that convex sectors with portals could be quicker than casting rays across a grid for every pixel column, except for some degenerate cases. This is because for any pixel column in-between the boundaries of wall segments, there's virtually no work to be done (O(1)), compared to the work of casting a ray along the grid O(n).

Btw, 286 played wolfenstein rather poorly. The 386 is rather more appropriate.

Wolfenstein was built in a couple of months by a then 21-year-old Carmack. He didn't focus on optimizing levels until Doom.