Not every 13" MacBook Pro has had four Thunderbolt ports; the base model always had just two. This computer clearly replaces that one, and Apple will launch another MacBook Pro in the future to replace the rest.
There was a model even with the touchbar that only had two ports and one fan. the four port model got you more cores and two fans, quite a different computer internally despite sharing the same shape and 13" macbook pro label. very confusing for consumers.