Not really. Emojis have become part of our vocabulary and no surprise that makers use them that often. It's a cheap and easy to way to make a landing look nice.

Although in the future, we probably will look back and perceive that as candy-buttons of web 2.0.

Well, you can now learn how to speak in emoji w duolingo
xn--h28h.duolingo.com/

In a casual context where it's users talking to each other (Social media, Slack & Forums) I think they add a lot of value. However when I see them on startups landing pages, I always think it comes as a bit tacky & I question their accessibility.

I think it has become too much and I see it as disingenuous if it isn't interpersonal communication. Emojis are like salt, too much and it is ruined.

I like emojis and don't mind them. I use them in my blog images (blog.amazingmarvin.com/), which is not the normal use case and hopefully less annoying to the emoji haters. ;)