1. Apple is increasingly a company who's primary growth area is through services revenue and Adobe is one of the most successful services-revenue companies around.
2. Adobe's bread and butter is essentially native desktop apps, one of Apple's areas of expertise.
3. Adobe is vulnerable today with a specific market segment, who resents the high cost, quality issues, and subscription-only model of Creative Cloud.
One thing I agree with is these wouldn't be professional tools the same way Adobe's tools are, they split the market between the high-end, which would continue to use Adobe products, and the low-end which would use these competitors. The low end would be content creators and smaller businesses.
The biggest flaw here is around #3, not sure how Apple can capture that services revenue without creating a suite that has the same flaws with consumers that Creative Cloud has? I think they could emphasize quality, and probably come in at half the cost of CC or less, maybe $25 a month. Maybe that's enough?