The idea of restricting immigration to those who could work is an old one. The federal Immigration Act of 1882 was the first US law to specifically insist that immigrants who couldn’t take care of themselves would be excluded.
That “public-charge” principle has been part of every subsequent federal statute on the subject. The landmark 1965 Immigration and Nationality Act liberalized the system, but it nevertheless allowed for the deportation of immigrants who became public charges within five years.
Moreover, far from being a Trump innovation, the likelihood of needing government assistance is already grounds to deny an immigrant a green card or citizenship.
What is different is that this rule broadens the definition of a public charge. Instead of being defined as receiving welfare payments, it will now also include the myriad benefits available under the ever-expanding welfare state that exists in the 21st century.