Currently, only about 3.4% of children ages 5 – 17 are homeschooled in the United States. Also, studies have shown that homeschooled children typically outperform their peers from both private and public schools.
So the movement is big enough to now be seen as a potential threat. That's what's implied by the Maryland politicos singling out homeschooling families. I'm sure there are hidden motives in the backrooms, to do with ideology.