I remember as a child coming to the same "if reality is a deception, at least I must exist to be deceived" conclusion that Descartes did, well before I had heard of Descartes. (I don't think this makes me special, it's just a natural conclusion anyone will reach if they ponder the subject). I think it's harmless for me to discuss that idea in public without someone saying "you need to read Descartes before you can talk about this".
I also find my personal ethics are stronly aligned with what Kant espoused. But most people I talk to are not academic philosophers and have not read Kant, so when I want to explain my morals, I am better off explaining the ideas themselves than talking about Kant, which would be a distraction anyway because I didn't learn them from Kant, we just arrived at the same conclusions. If I'm talking with a philosopher I can just say "I'm a Kantian" as shorthand, but that's really just jargon for people who already know what I'm talking about.
I also think that while it would be unusual for someone to (for example) write a guide to understanding relativity without once mentioning Einstein, it also wouldn't be a fundamental flaw.
(But I agree there's no certainly excuse for someone asserting that they're right because they're rational!)