It is FUD...most of us who made money in 2017 were in no hurry to file their taxes early...I wonder what date of filing they were up to?...plus some of us were hoping and still are...to get some clearer guidance from IRS concerning like kind exchange possibilities...
It is my understanding a Federal extension if filed timely...even without payment...will still be valid in terms of avoiding late filing penalty but late paying penalties and interest will be charged on any balance owed once filed...but this is not tax guidance...you need to do your own research...