There are so many companies in the market that the SEC nor FINRA spend time monitoring each one. It's all in a general watch over unless someone brings it to their attention.
That's true. But the SEC doesn't just pick up the phone, listen to a "tip" for 15 minutes, and then suspend the stock in question. They do their own digging.
FINRA's OFDMI also conducts investigations and makes referrals to the SEC.