Except markdown is not easier to read if you clutter your comment (as I've seen other commenters here do) with something like:

```

foo

bar

baz

```

```

note all the

extra

vertical

whitespace because regular paragraphs get a slight

gap

```

```

let's

throw

in a

third block

for some reason

```

As code blocks:

  foo
  bar
  baz

  note all the
  extra
  vertical
  whitespace because regular paragraphs get a slight
  gap

  let's
  throw
  in a 
  third block
  for some reason

The former becomes a problem in the discussion because it clutters the space and is harder to read than the latter, especially when you have multiple blocks around the discussion (in one comment or spread out across comments). You may not care, but using code blocks that offer a more compact and clear expression is certainly more courteous.