originally I introduced this to make it easier to implement the various APIs addPattern removePattern etc, but those were later removed in favour of simple getPatterns() and setPatterns(), allowing plugin developers to use ext-ds APIs to manipulate patterns.
However, ds poses a number of headaches because of mutability combined with by-ref semantics, which make it a pain to use these on the APIs because we can't guarantee that they won't be modified.
As much as arrays suck, they have two significant advantages over ext-ds: 1) they have copy-on-write semantics, and 2) they support PHP 8.0 without any extra work from me.
in pretty much every case, these usages really wanted to read the tag's contents anyway, which can be combined with a getTag() and instanceof call for more concise and static analysis friendly code.
In the few cases where the tag contents wasn't needed, it still wanted to check the type, which, again, can be done in a more static analysis friendly way by just using getTag() and instanceof.