Congress has spent decades ceding its power to either the President directly, or to the president in the form of administrative agencies. When they do vote on something, they end up voting on things that push the limits, such that they are effectively daring SCOTUS to rule. We shouldn't be surprised when SCOTUS does rule, given that scenario.
Congress is becoming a do-nothing branch. Have they addressed illegal immigration? Of course not. That would require a vote on a useful law. Agencies are doing all kinds things through regulations, and Presidents are doing all kinds of things through executive orders, that Congress should be doing themselves...which makes the presidential election more contentious, because more is at risk, as a new president spends his first week undoing executive orders from the previous president, and targeting agency regs. So, the country just goes back and forth with every presidential election. Not a stable situation.
Meanwhile, Congress just wants to posture, engage in political theater, and get re-elected (while getting rich on insider trading). Having to actually vote on things might cause some of them to be voted out of office (and then they might have to actually work for a living). Easier to give powers to the President or the administrative agencies.