Lightning protection systems are very sensitive to resistance in the chain, as any localized bit of it will cause a huge amount of heat there, and non-localized will cause current to branch out to other paths, also causing damage/heat. A typical lightning strike can be from 10,000-30,000 amps at millions of volts.

The damage from lightning doesn’t happen due to the current (as a first approximation), but rather resistance to the current causing heating/damage where the current ends up going - very rapidly, in a way the heat doesn’t have time to dissipate.

Having a working low resistance path to ground means heating (and hence damage!) is reduced or even eliminated.

For an example, see the steam explosion inside the tree here [https://youtu.be/3U8aoiEtVSg], compared to striking a grounded tower 6 times (no damage) [https://youtu.be/ScNzI76ZsiY]

The towers lights didn’t even flicker!

Unless carefully specified and properly maintained, the odds that a random cable or chain (especially when exposed to seawater) will maintain a low impedance path to ground is not good.