Apple wasn't thinking anything. The base entry level M1 and M2 chips do not have the GPU power to run more than one external screen. They are the cheaper base models. With base model GPUs. Some limitations are to be expected as the hardware is not powerful enough.
Apple made the more powerful M1 Pro, M1 Max and M1 Ultra options that do support multiple external screens.
Link-> MacBook Pro 14-inch and MacBook Pro 16-inch - Apple
One can assume similar options for the M2 chip will be coming in the future.
That's like asking why your cheap entry level car with no option packages doesn't have Leather seats.