Only in the case where both the acquirer and the target have directly competing products, which is why I specifically mentioned that case and said it would be the FTCs business. (And even then sometimes it doesn't. Google bought Waze, which was a direct competitor to Google Maps, but still both products exist.)
And, no, they aren't remotely equivalent statements to each other or to "markets remain competitive." If there are 100 products in a market, and an acquisition reduces that to 99, it will have no effect on the competitiveness of a market, which is why such an acquisition is not typically any of the FTC's business.
No, that's just wrong, if you let Adobe buy up all the design tools then you limit designer's choice to just Adobe. Will they come out with a competing product? Maybe. That's their business. But the potential is there, and Adobe has to stay on its toes and can't coast on it's near-monopoly status. Indeed, it's now also possible Figma will come out with products to compete with Adobe. And just the threat of that has the potential to limit all of the hostile behavior towards consumers Adobe has been up to for years.
Which is all to say that the market remains competitive.
If you don't think it's the FTC's business to decide whether or not that 100 to 99 move is significant, then I don't think you understand. Even if it's insignificant - it's their business to make that call. You can disagree with it, but if you think that isn't their balliwick, you're simply mistaken.
Hypothetical future competing products is a ridiculous standard. By that logic the FTC could block anything because the acquirer could always in some hypothetical future be a competitor.
It's ridiculous to suggest corporations will treat their customers better if they have competition? That if their customers have somewhere else to go they have more negotiating power?
Adobe and Figma are competitors, right now, regardless of whether they have product lines in direct competition, at this moment.
No they aren't. Having product lines in direct competition is the fundamental definition of being a competing business.
I doubt their executives agree that one another are not a competitive threat. They wouldn't have tried to merge if they weren't playing ball in the same court.