"And therefore" is, tragically, standard English. As is "albeit" and the egregiously awful use of "alright," "alternate" and "disinterested." There are so many really good, simple alternatives to these horrors, but the semi-literate and pretentious insist on using them. Therein lies the degradation of our beautiful language. But it's a fight that the great and good are bound to lose in this philistine world of ours.