That perhaps is something to ask the individual “platform” John.
You may be thinking of the trend towards brokers’ nominee holdings where investors don’t appear on the share register of the companies held. Where HYPs are held in ISAs, which for tax purposes is in my view advisable for most, there is no option and all holdings will be in nominee form. Where held direct, it is still possible to avoid nominees and hold paper certificates or use CREST, an electronic system which has the best of both worlds, being paperless whilst maintaining the holder’s name on the register. However both of these attract higher transaction and other costs so really only practicable for large non-ISA portfolios.
The advantage of nominee holding, outside an ISA, is the much lower transaction costs offered to investors so this has become very common even for non-ISA shareholdings. It has the further strong advantage of providing very simple online trading, which is not possible with paper though it is with CREST.
But yes, I agree there is a very small additional risk undertaken by using nominee services compared with holding direct, just because the investor is not a registered shareholder. As for compensation in the event of failure, I suggest as mentioned above that you ask your broker what may happen in that event.