Grumpy_Mike:
OTOH, other (most?) SMT chips and devices carry no such warning.
Yes they all do and always have. It is just that they have started to include this when you buy stuff in small quantities. Especially when you are getting samples from a manufacturer rather than a distributor.
Is that because more engineers and hobbiests are using reflow ovens to assemble prototypes rather than hand-soldering them these days or what? Do you know why this is a danger with reflow ovens and not for hand-solder methods?