Its true, some people manipulate Myfxbook to make their trading look better, but these people are usually trying to sell you something.
On the other hand, its a very useful tool to have for yourself. If you link your trades to it, it will produce some really useful information that you may be able to use to assist your trading. For example, you may find that you have a very poor success rate on certain pairs or at certain times of day, so you can choose to avoid these pairs/times in future.
If you find its not to your liking you can always shut your Myfxbook account, it doesnt cost anything anyway