To be fair, there are hundreds of different schools of Karate. Some are definitely more adapted to modern combat than others. Even so karate in general stands out in standing combat due to having a fair amount of striking techniques in its repertoire.Taekwondo is ok. But ain't no way Karate is an effective combat sport
If you want something for like an UFC competition you probably need to complement it with other arts that involve grappling because the fight often ends on the ground, but I personally don't think Karate is ineffective by itself to get that necessary first strike in or in an every day situation. Iirc, a decent chunk of competitive fighters even have some background on it.