Because in the modern era of the 2020s, they’re no longer considered correct by most writers and style guides.
So with apologies to stricter grammarians than I am, today, we’re going to get rid of some stubborn-like-a-donkey old “rules” once and for all.
1. Never use a preposition to end a sentence with.
This one’s been around for a long time, and it needs to be given the boot. It appears to come from early grammarians’ attempts to force English to follow the rules of Latin, which it doesn’t. This “rule” is unsupported by most modern grammarians because blindly following it can lead to some very awkward sentences.
Many of us are familiar with a quote widely attributed to Winston Churchill, although there’s some serious doubt he originated it, but no matter who did, it serves to point out how ridiculous that rule is! One of the versions is “This is the sort of English up with which I will not put.” Awkward to say the least!
The examples below show good grammar doesn’t always translate into good communication.
For what is it good? or What’s it good for?
With whom did you go? or Who did you go with?
Since the point of most business-related writing is clarity, abandoning a rule that never was a real one makes complete sense.
2. Remember to never split an infinitive.
The infinitive is verb form preceded by to – to eat, to read, to learn. Splitting the infinitive means putting a word in between to and the verb – to hungrily eat, to quickly read, to thoroughly learn.
This issue also comes from Latin where splitting the infinitive is impossible because infinitives in Latin are just one word. That type of infinitive is still found in other Romance languages whose root is Latin such as French and Spanish.
But English is different. Our infinitives are two words, so “splitting” them is possible. And sometimes the emphasis changes when we split an infinitive; if that’s true in one of your sentences, relax. If it sounds better, do it.
Do you recognize this one? To boldly go where no one has gone before. Sure you do. But how much energy would be lost by following the split infinitive “rule”?
To go boldly where no one has gone before.
Boldly to go where no one has gone before.
Nope. They just don’t work! The rhythm changes, and it’s not as strong a statement.
3. And don’t begin sentences with a conjunction.
Conjunctions are joining words, usually connecting words, phrases, and clauses. However, they can connect separate sentences. While strict grammarians might not agree, sometimes a long sentence that uses a coordinating conjunction (and, but, for, nor, or, so, yet) to connect the independent clauses sounds better when separated into two shorter sentences. Shorter sentences are usually easier to read and understand.
Beginning some sentences with conjunctions is acceptable to most modern writers.
Isn’t American grammar fun?