Paywalled articles are still openly available if you politely email the researcher. While we should strive to have no barrier, if you can’t afford to publish openly those who need the research can still acquire it under the table. Having research unpublished because the researchers could not afford to pay the fee is worse than having the research published in a closed journal.
I’ve gotten a few dozen papers from closed journals that way, and I’ve never been told no.
I’ve never considered that since I’m in cybersecurity, so the oldest paper I’ve seen that is from the late 80s. The majority is from the mid 90s onwards though, and due to the fast moving nature of the field anything that is old enough to have a dead author is likely out of date.