This is the case for a good reason.
The issue is with simply letting a descale solution run thru the machine. Dissolved small scale residue may wander thru the pipes finally reaching narrow parts and clogg them. Very prominent for such an occurence are the gicleurs, the orifice in selenoids and flowmeters.
When that happens you are exactly at the point of dismantling the machine, putting out the tubes, cleaning them in hot citric or other anorganic solution.
Actually that is how it is done right. The descaling in a non commercial environment should not occur that often, given your water quality is right and likely regulated thru a filter.