It’s one of the easy combustible material, so it’s part if not the main reason for the fire to spread and maintain burning until such disastrous level.

The other plausible culprits could be those netting and whatever combustible insulation layer they apply to the exterior of the apartment?

Debate & Pressure to Ban
Some experts — e.g. from the Hong Kong Institution of Engineers (HKIE) — have publicly argued for a ban, citing difficulties in uniformly assessing safety of bamboo scaffolding (variability of bamboo, weather vulnerability, higher risk over long-term use).
RTHK News

Others — notably workers’ unions — oppose a ban, arguing that many accidents stem from poor workplace management rather than bamboo itself. They warn a ban could threaten thousands of jobs.

PS: They rather listen to a bunch of lowly educated contractor worker union than the highly educated & trained Institution of Engineers?

I doubt you would see them covering so many buildings in netting if HK is under British rule (and standards).

This one is typical China cincai standard, very dun care about safety or human life.

But now Hongkonger put their pride on the bamboo scaffolding.
It is hard to pursue them now.