Trustpilot is also a place that takes money to delete bad comments if you pay them. It has been leaked before and there were mails from the staff members that said if you paid them X amount (changes based on how many bad comments there are) then they can delete some of it, and that made the overall point you got there better.
I am sure you can abuse it to promote your business, but their entire business model is based on blackmailing companies into saying "take my money and delete bad comments", that's how they are managed. Thankfully freebitco.in doesn't need any of that, they are already one of the most visited crypto websites, so they don't need trustpilot to say anything about them.
I remember a few years ago the Bitcoin.com admins had my negative review taken down when I complained about getting scammed on their knock-off version of Local Bitcoins. Looking at their page now and they have suspiciously gone from being a 1-star rated company when I originally left my review to being a 5-star rated company today. Almost all the positive reviews appear to be bots so it is obvious that these ratings can be easily manipulated.