They pretty much do have to suck. They arrive infrequently, stop frequently, accelerate like an overloaded lorry, and are only remotely feasible if your start and end points are on the same route. Switching buses is a huge time penalty. They only approach usability in urban hellscapes that are so densely populated, it makes my skin crawl.
Yet they keep putting them in small cities and towns where they take 3x as long to get anywhere as driving because of indirect routing, while causing traffic congestion because of frequent stops and low performance. Seriously, fuck buses.