That’s her thing, not a rule. I respect anyone’s personal practice, but this idea that self-readings invite bad energy is superstition dressed up as wisdom. Your Tarot practice is entirely your own; don’t let anyone tell you that you can’t do something with your cards (that goes for us, too).
Tarot cards are a tool, like a hammer or a pen. How you use them and the energy you bring can affect your readings, but the cards themselves don’t carry bad luck. If you believe they do, though, you might start subconsciously finding reasons to prove yourself right, and then you’re just living inside a self-fulfilling prophecy.
A whole lot of people say one should not or cannot read for oneself, and some have translated this as meaning it’s bad luck. But you are your own best guinea pig. And beginners need to practice somehow.
I do agree that it can be hard to give yourself a good reading for other reasons. The thread linked above on reading for yourself is a must-read if you want actual, useful spreads. I would also read this one:
Less specific about reading for yourself but it will help you actually get useful messages (it’s hard to do this for yourself).
Some readers just can’t get objective enough about their own stuff, and that’s fine, no shame in going to someone else for the heavy questions. But blanket-banning self-readings is gatekeeping.