One request I would make when implementing a spec for tables - don’t make a header required. For example, in kramdown, you can simply use
| Item 1 | Item 2 |
| Item 3 | Item 4 |
and it will produce a table without a header. I’ve used this style in many instances where I just need some information columnized but don’t want a header row. If a line of dashes are needed to start the table, that’s fine. But let’s not require a table head (most other implementations do require it, unfortunately).