I think the price jclardy quoted is for the 1TB MBP, which adds another $200.
But we're really just splitting hairs. The straight fact is that the MBP, similarly configured, is significantly more expensive than the Studio.
In exchange you gain portability, a great screen, a very good keyboard, and a fantastic trackpad.
You also lose a lot of I/O - one less TB4 port, 2 less USB 3.2 ports, 2 less USB-A ports, no 10Gb Ethernet - which would cost several hundred more to add via a dock and still leave you with less aggregate TB4 bandwidth. (As an aside: there are very few docks that even offer 10Gb ethernet, one such being OWC's and which is about $400).
There are also going to be plenty of folks whose personal/professional setup tasks their machine with hosting services for other machines and devices, many of which will get pissy and throw bit-fits if the various services they're expecting to see, don't live exactly where they were expecting them to, exactly when they were expecting to see them there.
There are many, many reasons someone might prefer - or indeed need - a desktop, and would have no desire to "make do" with a beefy laptop, particularly for more money.
This is *literally* why Apple makes both devices.