Diddy just read the fucking article they posted and it explains it to you. Artists don't give out more songwriting credits to randos out of the goodness of their hearts, the industry legal standard has completely changed. If a producer/friend/engineer/whoever is in the studio while writing and brainstorming is happening, and they throw out ideas along with the band, they're most likely getting a credit.
(In 2015) a US jury decided that Robin Thicke’s “Blurred Lines” had plagiarised Marvin Gaye’s “Got To Give It Up” and struck fear into the hearts of songwriters. “Blurred Lines” didn’t owe its melody, chord structure or lyrics to Gaye but it intentionally sounded like Gaye and that proved extremely expensive. “The decision was very unexpected and not at all based on established legal principles,” says solicitor Dean Marsh of Creative Law & Business. “It created a precedent that inspiration alone could lead to infringement. In the aftermath, a slew of opportunistic claims are being made on other hits.”
Rather than risk the time, cost and reputational damage of a trial, potential defendants take the pragmatic route of offering a share of songwriting in advance, which is how, for example, Right Said Fred ended up being credited on Taylor Swift’s “Look What You Made Me Do” without even having to call their lawyers. “You don’t want to analyse everything you write,” says Lindvall. “It can really paralyse you. There are so many songwriters who feel worried about the ‘Blurred Lines’ decision.”
This new industry norm can seem like a tediously legalistic overcorrection, but let’s not forget that the old orthodoxy bred many injustices. Band members and producers who made vital contributions were denied a slice of the songwriting pie; musicians died penniless, even as their work underpinned global hits.
Again, personally I don't have a problem with this type of shit. It only starts to rub me the wrong way when outsiders literally write songs/parts for Blink, which they openly talked about during the Cali/Nine days. They haven't talked about doing that this time, so I will assume they didn't go that route until there's any reason to think differently.