Further questions with a question about inversion in a conditional clause

Question

It's unlikely that anyone would have considered this project had the computer costs been 10 to 100 times higher, as they would have been 15 to years earlier.

Question 1. Is there a reason or a specific situation that one should use inversion in a conditional clause? Does that sentence sound different from "It's unlikely that anyone would have considered this project if the computer costs had been 10 to 100 times higher."? Since I am a foreigner, I can't get the difference..

Question 2. In the following sentence "as they would have been 15 to years earlier.", why can't I use a simple past tense. Like "as they were 15 to years earlier." Does this sentence have different meaning or is it not just not correct in terms of grammar?

Answer 1

Question 1: "had the computer costs been" is equivalent in meaning to "if the computer costs had been" - they are interchangeable. If I had to guess, the author wanted to avoid using a perfect tense of "to be" twice in a row:

.. if the computer costs had been 10 to 100 times higher, as they would have been...

By varying this a little, the sentence doesn't sound repetitive.

Question 2: the whole sentence is talking about hypothetical situations, whereas the past simple tense is used when talking about factual situations in the past. Here, the emphasis is that if you look at computer prices over some period of time, a difference of 15 to 20(?) years makes for a difference of 10 to 100 times in terms of price. Since there is a large amount of variability between 10 times and 100 times, and the author doesn't want to specify exactly how much, and whether exactly 15 years ago or more, conditionals are used instead of a past simple.

Here's a slightly different sentence that implies more definite knowledge on behalf of the speaker:

It's unlikely that anyone would have considered this project if computer costs had been 10 times higher, as in fact they had been 15 years earlier.