To be fair, the entire political spectrum in America is far right of anything in any other developed country. And so I agree with you, not all right-leaning people are unreasonable, take the US Democratic party, who I am to the left of but I consider reasonable. They are right-leaning -- they are a pro-business centrist conservative party. Democrats are so conservative they do not even support universal healthcare. Imagine in your country if the left wing party proudly campaigned to deny healthcare to the poor, but the right wing campaigned to deny healthcare to even more poor people and to give that money to the ultrawealthy. We have an actual left wing and its policy positions are popular if you take polls but there is almost no political representation of it or platform for it in traditional media.
It's tempting to pull out "both sides" rhetoric because reasonable people sympathize with others and try to see things from their point of view and assume since they believe something, there must be a grain of truth to it so they always feel like they should compromise. The problem is unreasonable people (or simply malicious ones) will take advantage of this impulse every single time and have been for decades. "But both sides!" is the climate that guarantees it's going to be impossible to have a rational or reasonable debate about political issues -- approaching a political debate assuming a compromise is inevitable and the other side is just as reasonable as you are is just accepting defeat before a single word is spoken. In this context, if both parties approach it with good faith debate can happen, but if not (as is our current situation) whoever is the most extreme always wins.
It's tempting to pull out "both sides" rhetoric because reasonable people sympathize with others and try to see things from their point of view and assume since they believe something, there must be a grain of truth to it so they always feel like they should compromise. The problem is unreasonable people (or simply malicious ones) will take advantage of this impulse every single time and have been for decades. "But both sides!" is the climate that guarantees it's going to be impossible to have a rational or reasonable debate about political issues -- approaching a political debate assuming a compromise is inevitable and the other side is just as reasonable as you are is just accepting defeat before a single word is spoken. In this context, if both parties approach it with good faith debate can happen, but if not (as is our current situation) whoever is the most extreme always wins.