And I don't mean to say that you're a bad developer or not smart enough if you use an IDE. Of course you should use an IDE with Java or C# or C++. Those languages are all very good, and when paired with a good IDE can be quite productive. And even with a Lisp, you should and will want to use a powerful editor or IDE with good auto-complete, linting, jump to definitions, etc.
What I'm trying to say is that to be productive in a Lisp, it's a different learning curve.
You just can't come and say: "well I tried it a little bit, and I couldn't figure out how to do anything and I was really slow, so I just don't get the point of a REPL and I don't get why people claim it's a hugely productive tool."
I'm telling you why, it's like complaining that you type slower on a keyboard than you can write by hand for the first year of you using a keyboard. There's a learning curve.
You can't just say: "well I can't figure this out. Where is the IDE to help me with it? Where are the type definitions? Where is the compiler to guide me? I guess the Lispers are just full of it."
No, you didn't do what Lispers do. Lispers learn the language until those things are no longer a problem, and then they unlock a new found productivity combined with the ability to work inside a running program, quick iteration, being able to extend and mold the language to what is most efficient for you and your problem, etc.
It's 100% ok if you say that you don't feel it's necessary for you to go the extra mile to learn a Lisp properly. That's fine, if you find you're sufficiently successful and productive already with your language, that's totally cool. But you can't not properly learn it, and then claim that the claims of those who have are invalid.
It's like if you started to doubt a touch typist that's telling you that learning to touch type makes you a more productive typist, because when you tried it was hard to learn and you were slower at typing.