Like many other decisions we make in the outdoors, it is a question of assessing the risk involved and whether you think it is justified. I could imagine circumstances where it could actually increase your safety, e.g. if you are carrying a big heavy pack and the summit involves some hard scrambling.
The risk of not being able to re-find your gear is a real one, and can be mitigated by using a GPS waypoint that you can easily navigate back to.
I agree risk management is personal so I suspect we'll have from agree to disagree on this particular issue.
To reply specifically:
1) heavy rucksack + hard scrambling= bad planning/ route choice if you're not confident enough to do the scramble with the rucksack.
2) you're assuming you can get back to your rucksack to find it, which is my main point.
For me it's a hard and fast rule. There's enough risk to be found out there as it is, and our lives are spent mitigating it but not having your rucksack with you all the time seems a strange and pointless risk to take.
Cheers,
James.