The IoT space is awash with "platforms." If you were to search the web for "IoT Platform," you would be overwhelmed. One reason I can think of is that it’s a development environment; another is that it’s a fairly complete and general software stack that includes many common functions encountered in IoT applications. Still another is that it is a combination of specific hardware (computing, communications, and some storage) that is broadly applicable. If you do a casual search on the web, you will find many examples of the three aspects I have mentioned. To be practical, the choice depends on the vertical in which you are building applications. The Eclipse Foundation did a survey of programming languages used and identified over twenty as “musts” and in common use. No platform deals with that well.