You're assuming a oot about the people who use these programs. If you wanna hate on the program itself, sure, be my guest. But, please, don't insult their users. It achieves absolutely nothing, and only makes you come off as rude and presumptuous.

A large audience for these types of tools is people for whome English is not their first language (this includes me, so please forgive any spelling/grammar mistakes you may find). This audience may be very eloquent and stylistic in their native language, but learning languages (especially when you have passed your teens) is hard, and sounding professional and sleek requires a lot more effort than you might think.

Here's where Grammarly comes in. It reformats your sentences to be more consistent with your projected attitude, removing a ton of work for some people.