Imagine a flyer promoting slippers for men.
That would ruin the message of the flyer which is to promote slippers for the male demographic! Hence be cautious when choosing the style of font for your promotional material - whether that is for a website, banner ad, poster, social media post or even for a logo. You might think - fonts are not that important! What matters is that a certain text can be read without hassle.
You are right in some extent. It needs to be read clearly but the style of font is a important component of your design just like the type of image you include in it. The type or the overall appearance of a font can symbolise something. Obviously your aim is to symbolise a message related to your brand. A bold font could represent something important or a cursive font could represent something hand written. Just like a image which represents something, fonts could represent anything and should be chosen to represent the right message.