It's really not the examiner who makes the decision. Management has pushed the "99% of preambles are not limiting" idea onto the examiners.
This is something I've been railing against here for a long time. I understand that, in many situations, the hands of the examiners are tied and management forces them to make rejections that are contrary to prevailing US patent law.
The law on this issue (limiting effects of preamble language and prosecution history estoppel) is quite clear; if the applicant says that language in the preamble is limiting, it is. Period.
I'm still hopeful that the recent change in administration will result in a PTO that follows the law with greater fidelity.
Regards.