What is the essence of switches in Mikrotik routers and what is the difference where the ports are connected directly?

Question

network hardware

There is a feature on the diagrams of Mikrotik routers, in cheaper models, the ports are grouped by switches and then there is a connection to the processor.
In more expensive solutions, the diagrams show direct port connections to the processor.
Could you suggest what are the features of the solution with switches?
Does it impose restrictions on the use of functionality by restricting the part within a group of aggregated ports? Perhaps there are other features?