Thats true praxx, it is absolutely horrible for F2A category of GC holders. They cannot apply for B1/B2 visa, as they are potential immigrants. One friend of mine had a GC, after a year of getting GC, she married her boyfriend from India, year 2 of marriage, they had a daughter. The daughter was born in the US with a heart problem. The husband tried B1/B2 visa 6 times. All the times he was denied. My friend had to stay in US as the daughter was a US citizen and was getting good medical care from 'ALL KIDS' which is a govt insurance program from kids only in IL. The spouse had to wait 4 plus years outside. Finally last year my friend became a citizen and within 6 months the spouse was here, now has a GC.
I feel this is ridiculous. The poor sick child grew without knowing her father till he came here. My friend could not take the child to india as the child underwent 4 surgeries during this time.