I've been using Adobe for 20 years probably so I'm very familiar with shortcuts and workflow. It's an extension of my hand. Its popularity means access to a large community of third-party tools and tutorials.
As a freelance designer I budget the $600/yr for the Adobe suite because I get ALL their software - Photoshop, Illustrator, InDesign, AfterEffects, etc. Sometimes my clients need a new logo, custom graphic, layout for a report, or video editing. So using the suite for my illustration work just makes sense; I already have tools.
Krita looks interesting. I have never heard of it. To make it more popular, they'd have to raise awareness of it somehow and address the Adobe customer pain points.
Most don't like the subscription model. Affinity does a good job of addressing this on their website - their program is $50 once. (Psychologically I also like that they aren't free, though I'm aware open source stuff isn't for-profit)
They don't want to change ("I've always done it this way!") They know Adobe and can just "go" on whatever project they need. Stopping to learn something new is an ordeal. The biggest hurdle is probably getting them to try it. Advertise how easy it is to switch. Getting Krita into schools is a great tactic - whatever students learn on they tend to keep using later. Then businesses would want to convert to whatever software the designers are using.
They have invested money and time into learning Adobe so attacking their decision would likely put them on the defensive. Using phrases like "shelling out money" and "industry standard whatever" doesn't move the conversation forward. The persuasive argument is focused on benefits. I would refrain from the "corporate agenda" angle. Show amazing art made with Krita (because we all want to make great art), ask "have you tried this?" oh, and it's FREE!
Maybe convince some popular artists to try it and review. YouTube demos and word of mouth can get some traction. Get people excited about Krita, don't put them down for using Adobe. (I know you're just ranting here, I'm just saying people can be sensitive to negative language and might take it personally even if you didn't mean it that way.) Change starts small!