Any arrangement that uses an RCD to cover multiple circuits is at risk of causing a inconvenience issue, its a compromise which can be tolerated in most domestic environments, however in commercial situations, you generally have more of an inconvenience (however many folk left going for a brew/smoke while the PCs come back on line) and more equipment likely to have a standing earth leakage.
As to RCBOs, yes they reduce the problem (sometimes they can still cause a nuisence trip issue though - damp heating elements on cookers etc, ballasts in outside fittings etc, also seen multiple RCBOs drop out when a storm passed near by). But they are expensive (look up the price of a merlin gerin rcbo and muliply it by a 12way TPN board loaded with them!). They fill the board up and make it tight to work in, most makes have a flying earth lead which must be disconnected before a global insulation test is carried out. Earth loop readings take longer to obtain and more likely to be prone to error. Some makes only available in C type so you might have to swap your zs being in spec for an RCD, which is a poor deal.
In short, they are not neccessary, and add expense and time to the job without good reason. If I have a radial circuit feeding a panel heater in a mess room, what advantage will be gained from swapping the 16A MCB to an RCBO?
Its not unusual for specifications to require that no RCD is fitted to lighting circuits, since the 17th came out that has required that switch drops are in metallic conduit (the same specs would have already required them to be in plastic conduit under the 16th)
