There are a lot of reasons that's why an exact match domain would not rank well in Google or other search engines like Bing. An exact match domain is still a somewhat beneficial factor in search engine ranking, but less than several years ago. The site has to be an authoritative site with quality content and at least somewhat trusted sites linking to it.
There are some reasons that domain name exact keyword match content does not rank in Google as follows:-
1. The website is brand new and has not acquired history.
2. The website has thin content which means the content isn't very valuable.
3. The website has little or no unique content.
4. The website is not properly optimized to connect the relevant keywords to good-content pages.
5. The pages are targeting unrealistic keywords - those keywords that are too competitive.
6. The website has no valuable links coming to it from other respected or industry-relevant websites or trusted websites.
7. The website could have technical coding problems causing pages to not get indexed properly on Google.
8. The internal linking on the website doesn't even indicate what the pages are all about.