In FFXIV, it makes sense because that's how video games work, and the mechanics of the game are designed so that some amount of failure is expected and OK, allowing players time to learn and adjust.
In the TTRPG, it'll depend on how the encounters are designed and how experienced the playgroup is, as well as how the GM narrates. If players have no clue what a specific marker/invoked spell does, they may not know to stack or split, for example, and leaving a healer with a stack marker to receive all the damage alone will basically spell the end of a run. The stricter adherence to job roles will also mean that if a tank or healer goes down, the likelihood of a clear also drastically drops.
For playing through the in-kit scenarios, I'm likely going to let my group retry as many times as needed, even offering a version of the Echo if they need it (increased health and bonus to all ability checks depending on how far into a fight they got).
If we ever get to homebrew scenarios or a longer campaign, I might have a squad get wiped, and then allow them 1 chance to "rescue" the original squad with a set of backup characters.
The starter kit also denotes that death is a real status that can happen; it's just up to you as GM whether you want to deal with adventurer death or not. Does it help tell a story? Or is it a hindrance to building any sort of narrative coherence?