It is not an bubble .It is real life accounts created on steemit.
Also I agree and dis agree on the part you wrote "who you know" , let me explain, if you do know people on steemit or you do get a punch of people on steemit you know it would work to get more upvotes but if you post stuff that actually makes sence or is true or alot of people can find the info helpfull you will get more followers and more upvote.

Back to steemit, remember all this new accounts thats signing up is really good ( not a bubble) and steemit interface can handle all of this accounts. steem's blockchain can handle a-lot more new accounts ( I have read somewhere that its only using 2% of its capability at the moment)