Well, I don't think that a sharp increase to $20 would be useful in a short time for HIVE blockchain.
It is very useful. It will drop again in price, but it brings attention. When thousands of accounts are earning thousands for a few week, it attracts attention.
There would come up a lot of new users who would come just to earn some $ with their poor quality posts and probably plagiarism.
This happens now at any price :) Many people joined in late 2017/ early 2018 when Steem price was up. most left - some are now orcas and a couple whales.
I remember the price of Steem was $8-$9 and there are many people from my country. Now not like that despite the recent ups.