Google announced in the Google My Business Help forums that owners of businesses within Google My Business can now reply to reviews directly using Google Maps on desktop. Prior you could do it in Google My Business, in the Google My Business app and in some other forms. But now you can also do it right from Google Maps on desktop.
Kara from Google wrote "We’re making improvements on how you can reply to reviews, and providing you with more information and tools to get feedback from customers. You can now reply to reviews directly with your business profile on Google Maps from your computer." She added "Replying directly from Google Maps lets you manage your reviews without having to download the Google My Business app or open its homepage. Learn more about how to read and reply to reviews. We also have some tips on how to respond to negative reviews. Positive or negative, reviews are an opportunity to identify areas to improve the consumer experience."
Here is a screen shot of how it looks on desktop:
Here is a help document on other ways to reply to reviews.
Forum discussion at Google My Business Help.