Here is what i noticed about Titanic Captains:
1. They are Designed to be Ruthless & Corrupt Criminals who enjoy Hurting Others
- This indicates to me that each Captain is meant to Endanger a Group of People
2. They are Designed to be Island Level Threat, their Abilities cannot be Contained in a Limited Space
- This indicates that each Captain requires their own Island as their Fight Arena
3. They are Designed to have Tricky DFs, each Captain can Single-Handedly Counter almost any Army
- This indicates that Strength, Size & Numbers are Useless against them
4. They are Designed to be able to Infiltrate other Locations thanks to their DFs or easily Take Control
- This indicates that They don't need to be Together, each Captain can be sent on a Mission Alone
So Overall, these Captains are Designed to only Shine when each one is taking on a Nation by themselves, not Pure 1v1s,
This leads me to conclude that Blackbeard Pirates are Created to Counter a Specific Group of People who are divided among Multiple Islands,
And they include Very Powerful Armies who are extremely troublesome for the World but an Easy Prey for BB Pirates,
These seem to be Kingdoms of Giants beside Elbaph, it's obvious They will eventually answer the call for Ragnarok or End Battle,
So Titanic Captains Job is to Stop their Armies, this is why They are treated as "Captains" rather than "Commanders", it's cuz each one gonna have their own Incident,
It's why Oda gave Laffitte Wings, gave Doc Q his Flying Horse, gave Auger Teleportation, gave Pizarro Ability to merge with Islands, gave Devon Shapeshifting Abilities, gave Shiryu Invisibility & even Sanjuan Wolf might simply Infiltrate his own Origin Island ... etc
Now to Save All Giants, it doesn't become a question of "Who can Defeat this BB Commander?", instead it's a Question of "Who can Save those Giants from that Particular BB Commander?" (It's actually possible that this entire Holy Knight Incident before Imu's Arrival was a Lesson for SHs to Prepare for Tricky DFs & pick their Opponents Carefully, rather than being Unprepared for a Fight),
For example, Laffitte will Use his Hypnosis on his Target Army, so before He is Defeated, those Giants need to be Saved First, and the only SH who is Created to Solve that is Brook,
We also have Augur who can Snipe Giants from unreachable Distances, only SH who can stop him is Usopp,
We have Doc Q who's gonna make Giants Sick, so only Chopper can Save them,
We have the Arsonist Vasco, and We've seen how Giants desperately need Jinbe to stope Huge Fires,
... etc
So imo Titanic Captains (With Exception of Aokiji) are only Created to Delay Ragnarok & spread their Corruption, while SHs gonna Use their Skills to Save the Day, and after those People are Saved & BB Captains Powers are Countered, Oda can simply draw them getting One-Shotted by SHs similar to how Hody's Commanders were Defeated in a similar fashion,
It's basically JoJo's Style Fights, and They will help each SH have their own Incident & Heroic Tale & Island that worships them.
So Regardless of how Strong People think They are, i will always see them as mere Hype Tools for SHs.