Thing about Rangers is less the sectarianism, more that their sizeable firm has affiliated itself with the old C18 elements & remnants at Chelsea & Portsmouth, along with the plethora of fascist groups tied to clubs like Inter & Lazio for decades. Agree this is not indicative of every supporter, but it’s never been rooted out fully because the club like to keep it quiet.
Not justifying old firm stupidity, rather there are more malevolent forces at work, but when they got relegated to hell & back while the entire club imploded, that was art.