I think you're missing the point of why that phrase became a bit of a joke and is considered unhelpful. It's not written off because people think mitochondria are unimportant or should be written off, it's because when you're a teen learning this stuff and they're trying to explain how cells work, mitochondria are a particularly strange and complicated thing that's thrown in to the mix, and it sounds important and complicated but in lieu of any real details there's the sudden brick wall of this weirdly uncharacteristic phrase that doesn't really sound like how you're teacher normally speaks, doesn't really read like how the rest of the textbook reads and other than some vague allusion to "power" fails quite spectacularly to tell you what mitochondria are.

Part of what made it maddeningly confusing was that these lessons are getting you thinking about how mechanisms can coalesce to form larger systems, encouraging you interrogate macro scale phenomena down to the smallest scales and see how it all ticks and then suddenly they hit you with this magic "powerhouse", very poorly explained, and which because of that poor explanation appears somehow irreducibe. You know mitochondria have "power" of some sort but any of their own mechanisms are conspicuously left out of the picture. This is probably for good reason because of the difficulty of making a syllabus that isn't too deep or broad for the time available and for teenagers to pick up but it's a very sudden brick wall. HOW do the mitochondria power cells? Do the mitochondria have cells? Do the mitochondria's cells have mitochondria? How are they transmitting this power to our cells? The way this phrase was used was more reminiscent of a slogan, or an ad campaign and quite unlike much of anything else one remembers from biology class, it felt very... out of context. Even the choice of the word "power house" always felt weird, as it wasn't for me at least, a word commonly encountered so to use it as an analogy really undermined it's ability to help you grasp anything as it sought to explain one concept in terms of another only vaguely understood concept. I gathered this was a similar term to "power plant" although other than a popular museum in Sydney I had never heard the term used outside of that goofy phrase and to say mitochondria function similar to a power plant, in that they produce power doesn't really say much more than, "mitochondria are the energy source of cells" which is similarly meaningless in all but the most basic sense.

So, don't blame the mocking meme for dismissing mitochondria, blame the weird ass phrase the meme mocks for completely failing to explain anything about them and relegating them to a single, cryptic, hand waving sentence.