Dear OP,
I will assume you are trolling. But in case you are not, or in case anyone agrees with your opinion, I suggest the following perspective:

FFXIV has content for a wide range of players. Most of the game is accessible to you already, requiring little to no playing skills beyond logging in, basic navigation and pressing 1-2-3 in that order repeatedly. However, you are correct that Castrum Fluminis, among other fights in the MSQ, require actual gameplay abilities and may benefit from practice, meaning its possible you fail.
Now, seeing how somebody struggling with Castrum Fluminis has already completed most of Stormblood, you have the core game and 2 full expansions of content available to you already. There will be content further down the road that you will never be able to complete, and you will be equally unhappy when you find out not everything was designed to accommodate entry level playing skill (1-2-3).
As such, and seeing how you seem thoroughly disturbed by having to try multiple times to beat Castrum Fluminis, and will possibly one day encounter even worse content that will leave you angry, lost, sad and confused, I suggest the following: Let Castrum Fluminis be your characters finale. This is YOUR Eorzea, and as so many players here unwilling to extend their gameplay skills to access content they deem hidden behind "walls", you can just decide that having access to months and months of content is enough, and your story ends at the feet of Tsukuyomi (nice feet, too!). you will see players with gear from distant lands and strange bosses that you have never seen, but that would always have been true, no matter how easy Castrum Fluminis is nerfed down to be.

I know players who play less than you, have more responsibilities in RL and still manage to beat the odd Savage raid. Its not the demanding real life that is your wall, its not the overly hard design of castrum fluminis that is the wall - the wall is in YOUR mind. But it would require effort to overcome those walls, and its a game after all ,right?
So I congratulate you on a fitting end to your heroes journey - he/she certainly saved Eorzea enough times before Tsukuyomi finally took her down,right? Let your hero, finally, rest.