In my experience, this is not true.
In mine it is when these passengers arrive uninformed of their flights change of schedule etc.
FR did the same for me on the one and only time I have booked with them - ironically a day trip taken just to see what the "Ryanair experience" was all about. The outbound flight was delayed and delayed and delayed. The aircraft for the return flight was not - I could see that it was boarding and ready to depart on time. I called FR who could immediately see that if I waited for my outbound flight to finally depart I would definitely miss the return flight, so they canx the res at that stage and gave me a full refund. That was also the right thing, and it confirmed to me that I shouldn't clamour to fly FR again.
That was an unsual decision for them to make. From my own experience we have offered refunds to passengers on the single outward jounrney of their return flight , however ryanair would argue that return single sector flight is still valid and can be used without the outbound flight.
. FR would have known perfectly well that it was intended to be a day trip.
Looking at the booking I would agree, this is what it would look like to me , still does not change the fact they have no legal requirement to get you to your destination before returning you when the passenger chooses to book flights so close together.
Ryanair : Ryanair is strictly a “point to point” airline. We therefore do not offer, and cannot facilitate, transfer of passengers or their baggage to other flights, whether operated by Ryanair or other carriers. We recommend that passengers do not book onward flights on Ryanair services. Ryanair assumes no responsibility for making connections and therefore will not be liable for any losses or expenses arising out of any failure to achieve a planned connection.
Ryanair : E-mail contact will be made to the e-mail address provided at the point of reservation in respect of any schedule change or advance cancellation to flight itineraries. If you have not provided Ryanair with a valid e-mail address, you should reconfirm your outward/return flight timings between 24 and 72 hours prior to departure.
Ryanair : Carrier undertakes to use its best efforts to carry the passenger and baggage with reasonable dispatch but times shown on the ticket, in timetables or elsewhere are not guaranteed and form no part of this contract. Carrier may without notice substitute alternate carriers or aircraft or may alter or omit stopping places shown on the ticket in case of necessity. Schedules are subject to change without notice. Carrier assumes no responsibility for making connections.