There is a confusion between the tool and the purpose.
A slide deck is a tool. But it can serve many purposes. Therefore the format should serve the purpose.
I see three main purposes (although there are plenty others too):
Support for a Presentation You want your audience to understand and you are here to present.
Support for a Pitch or a Talk You want to convince or inspire your audience and you are here to present.
Reading Material You want your audience to understand but you are not here to present.
In the first case, you want your slides to be complementary to your discourse. You want them to present visual information that might be too complex to put into words. There is little purpose duplicating what you say and what you put on your slides. The content should be complementary, not redundant. There is generally a good balance between what you say and what you show, since you don’t want one to overpower the other.
In the second instance, it’s all about what you say. Your slides are merely a reference point for your audience to understand the structure of your argument. Those slides tend to be highly visual and deprived from having much text. Many may not have text at all. They are like a background on which your words get additional depth.
In the third example, you are not here to make the argument. So you want your slides to be very thorough. The slide format is just about presenting the information in a landscape format, which is usually preferable if consumed on a screen, but it could as well be a report.
Whenever you need to make slides, be clear about the purpose you are aiming, and don’t mix the formats. There is no such thing as great slides. It all depends on what you’re trying to achieve.