Wow. How did I miss this post?

You are 100% spot on. Anyone that buys or sells any significant quantity of anything should do OTC trading - a large amount of BTC trading (the really big deals) happen this way and they don't impact the price. This is how the big guys and the people who are already wealthy make their buys/sells. I first found out about it when I read about some people who were moving from trading stocks and shares and diversifying into Bitcoin.

They wanted to invest millions but knew that if they made a buy like that on an exchange it would likely cause a sharp rise in price (increasing their buy in cost before they had completed the trade) followed by a likely compensatory fall.

The end result would be that they would actually lose money and destabilise the price by doing this. They were using special brokers that are not available to us regular people but the principal is the same and we have the options of Blocktrades/Shapeshift etc.

The problem is that all of us small traders in the end give the same effect as one massive trader. The market is a balance between differing interests and if you are interested in minimising your effect on the market OTC trading is a great way to go.

I hadn't really thought about using Blocktrades for my purchases but was instead exchanging my bitcoin/other cryptos to SBD on exchanges. Next time I will see if I can just do a direct conversion via Blocktrades or if they aren't able to do it I will try Shapeshift.

This is even more important for those powering down though because each time they sell on the exchange markets they potentially put downward pressure on their own next selling price - in essence harming the value of their own assets.