There are great reasons for using PowerPoint. But there are also awful reasons for using PowerPoint. The worst reason to use a PowerPoint is this idea that oh, I don't know what to say I have a bad memory. If I just put it all on bullet points. I won't have to spend time memorizing, rehearsing practicing. I'll use it as my teleprompter.
It's the poor man's the poor woman's teleprompter. That's the worst possible reason to use PowerPoint slides. PowerPoint slides are there to enhance the experience for your audience to make the ideas you have more understandable and memorable for the audience. You should not be using the PowerPoint slides as a reminder for you and what to say. If you want to remember what to say if you want to have an outline a structure and know exactly what to say. Whether you're speaking for 30 minutes, 60 minutes, an hour.
There's Far better technology than a PowerPoint deck. And the technology is called a piece of paper. Here's what I'm using if I'm giving a speech for an hour, and I'm not using PowerPoint, a single sheet of paper, a few bullet points, large thoughts. So, again, we're here in a PowerPoint class. I'm not here to talk you out of PowerPoint, but I want you to use it the right way. Don't use a tool that works for one medium and put it into another one.
Don't ignore a tool that does work. Paper, works great for a speaker if you just want to remember what to say.