Publishers in general are very bad at preservation. Entire runs of journals often vanish because the publisher went bankrupt, sold some assets or just didn't bother to do their homework.
For this reason, customers (mostly libraries and universities) around year 2000 have started demanding that the closed-access publishers have preservation mechanisms and provide dark archives to ensure access after subscriptions expire or are otherwise breached.
This has resulted in initiatives like https://www.lockss.org/ and https://clockss.org/ .
> Since CLOCKSS launched in 2008, 53 journals comprising 13,000 articles have been triggered
That's 13k articles (mostly from closed-access publishers) saved from oblivion, but there's many more. The English Wikipedia alone knows thousands of articles where even the DOI is broken (usually they're from publishers like Elsevier, Wiley, T&F, LWW, OUP).
https://en.wikipedia.org/wiki/Category:Pages_with_DOIs_inact...
On average, fully open access journals present a much lower risk of vanishing because they're easier to archive, especially if they use a [free license](https://en.wikipedia.org/wiki/Free_license) like CC BY or CC BY-SA. However, publishers still need some nudging towards archival.
DOAJ requires a digital preservation plan in place (at least with CLOCKSS, LOCKSS, PKP PN, PMC, Portico or a national library) for a journal to be granted the [DOAJ seal](https://doaj.org/publishers#seal). At the moment there are [about 1400 journals with the DOAJ seal](https://doaj.org/search?source=%7B%22query%22%3A%7B%22filter...).
Authors can publish in a journal with the DOAJ seal and be sure that their work is safe. On the other hand, they have no recourse against a commercial and closed-access publisher, which can be forced to comply with archival only by contracts with its paying subscribers.