The cable thing is simply due to physical limitations. If you want a data cable with the fastest data rate it will be maximum 1m (or ~3ft for the metric challenged) and quite thick and stiff. A cable exclusively for charging can be quite long and thinner so it can be coiled smaller. Then there are various middle grounds with slower data rates, which sometimes are too slow for certain applications (e.g. Android Auto).

If you buy a short, thick and expensive cable rated for thunderbolt 5 you can use it for everything, but you may not like the form factor.