It's been like that as far as I have seen. Just the range of price differ. 
Will be good to see it in opposite heights.

Sell walls only stop price increases, they do not drop price.  Also, some sell walls can be faked, as well as buy walls faked.  For example, as a coin rallies, you might see a huge buy wall on the way up... often a fake buy wall.  It vanishes often followed by a crash.  Buy / Sell walls are often use to manipulate market perception, rather than as an accurate gauge of demand, but I do not think this applies to Steem.  Likely, they are long-term holders, willing to sell at a fixed price and no lower.

Because their are apparently no sellers who are willing to sell their Steem for the price that will meet up with the highest buy order. 

The sell walls you see could however  potentially  make it harder for the price of Steem to rise.

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