And that's why I suggest an intelligent approach to the problem, rather than simply preaching "don't do it".
Many riders will take great care to stay out of door zones, yet then filter without a second thought, which is an inconsistent approach to the same danger.
And you are correct, in that the traffic environment presents dangers, but being stationary traffic may be safer that filtering, depending on road layout, traffic volumes, weather, time of day etc. There is no universal correct answer.
Leaving ASLs aside for a moment, many people filter to avoid being surrounded by the dangerous vehicles as you describe, then place themselves in an even more dangerous position at the head of the queue. Unless the lead driver has very considerately left a nice dollop of space this position likely compromises safety far more than being 4 or 5 cars back stuck in stationary traffic.
Filtering can be safe, often it can not. More often it can be done safely, but most of those who participate do not do so.
I'm doing an advanced road skills course in Wiltshire in June if you fancy coming across.