Because not everyone have technical skills and knowledge to invest in masternodes alone. I have a lot of friends who lose a lot of money with masternodes too! Some1 will prefer to deposit there and only get profit after that.
In this lifetime, You don't need any technical knowledge and skills to run a masternode. Almost all masternode has 1 click installation script and there are more shared and masternode hosting services that that offer turn key solutions.
So there's no need for a investment platform for masternode coins.
If you dont have right information in which MN with HIGH ROI to invest, in 90% of times you will be scammed. Thats why there is a chance to avoid this, and only invest a little amount there
. Its not like normall ponzi scheme. Its a website where owners can pay us with their income from our investments.