Old houses are/were drafty and leaked air all over the place so any moisture had a chance to dry out, they were made with real wood as opposed to engineered wood products also.
When asphalt shingles came out I suspect that they were marketed as the new high end roofing material that would solve all of the problems with cedar shingles.
People took these asphalt shingles and installed them over the top of cedar shingles, this changed the physical dynamics of the roof assembly dramatically.
With asphalt shingles over the cedar shingles the roof could no longer breath so this lead to massive ice build up and leaking.
Now that the house doesn’t have the air exchange that it used to the moisture from leaking didn’t get an opportunity to dry out, leading to rot & mold.
It seems like it took a few decades for people to figure out what was happening and the underlying cause.
This is the result of a vapor barrier on a building that wasn’t designed to be air tight.
Nowadays and even for the last couple of decades we have been building domiciles that are more air tight and require a different approach than homes of 100 yrs ago.
If you have a newer home or a home that was designed with ventilation in mind it matters not whether your underlayment is a vapor barrier or not because the building is designed to handle it, if it is working correctly as a system.
In some specific cases this is very important but for the vast majority of sloped roofing rooftop vapor barriers make no difference.
If it is an older home that originally had cedar shingles on it there needs to be a proper cedar to asphalt conversion done, this would include the installation of a roof ventilation system.
I personally prefer asphalt felt also but felt that meets the minimum standards doesn’t exist in my area, the only asphalt felt available to me is complete junk.