I have read it, and Dijkstra is a good call to authority, but I don't agree.
His opening sentence is instructive: using the 'pernicious three dots', everything is totally clear: with an ellipsis, it's impossible to understand anything other than a closed interval.
It's primary school mathematics that 2 <= x <= 12, i.e. the interval mathematically written [2,12] (or 2,...,12), contains 11 integers. A programmer who doesn't understand that is in a world of trouble as half-open intervals won't stop the inevitable rain of off-by-one errors.
A programmer who actually calculates the size of a list in the way that Dijkstra suggests (specifically, by calculating b-a) is also perhaps acting questionably.
Dijkstra's argument here might make more sense when correctly framed in 1982.
As an aside, if Dijkstra would agree to use a fully-closed interval, his suggested advantage of 0-indexing is eliminated and he would presumably then prefer 1-indexing.
They are inconsistent within two characters: closed on one side, then open on the other.
If the notation was >my_list[0:3) at least it would be mathematically appropriate.