A connection to an FR flight is anyway not allowed to use the Flight Connections facility. I had a long exchange with DUB a few months ago on this because nothing was (still the case) indicated on the flight connections board indicating this restriction.
It appears to be a Dublin Airport policy restriction (the connection fee is lower than the normal passenger departure fee)
It would be a bit late for passengers who would only first notice it on the Flight Info Screens....it is however stated on the website and surly people booking a connection would look to see if the airport has connection facilities.
Under the Self Connections Page
Please Note: Self-connecting passengers are not permitted to use the Flight Connections facility
On Ryanair Website
Ryanair is what is known as a ‘point-to-point’ airline. This means that we fly directly to our destinations and we do not operate connecting flights.
This means that we cannot transfer passengers or their baggage to other flights, whether those flights are operated by ourselves or by other carriers.
For more information please refer to our Terms and Conditions of carriage here.