It is perfectly general, but the error rate is too high to operate all qubits simultaneously for more than a few tens of gates without error. This is why error correction is needed but then you need orders of magnitude more physical qubits to deal with the overhead.

Then why can they perform an RCS evaluation but not some other algo? RCS requires the least number of qubits by a huge margin?

No, not quite, it's about the error-per-gate. RCS has very loose requirements on the error per gate, since all they need is enough gates to build up some arbitrary entangled state (a hundred or so gates on this system). Other algorithms have very tight requirements on the error-per-gate, since they must perform a very long series of operations without error.