The bitterness of the attacks by FG towards SF is not simply political, its existential. It's from not only a political party, but from a certain class of people, fighting for their very future, and what they see as their birthright.
Look at the dynastical nature of FF and FG
they have generations of families who carved up the spoils of power in Ireland. People who were born not only to be TDs, but judges, civil servants, state board members, media jobs, cllrs, etc, charity executives etc etc. For every FF person in a high office job, there is a
FG "mirror" also in one. Labour got crumbs from the table. High level trade union jobs, low level State board jobs, and they didn't rock the boat.
SF threatens that. SF do not have the people "embedded in the fabric of power".. so FF and FG are frightened they'll rip it up
SF have "nothing to lose" by shining a light on how power is administered in Ireland. And that frightens those operating in the shad