There are some great business people out there, don't get me wrong. You just need to be very cautious if you don't already know the people. And yes, those skills (negotiation, marketing, management) are extremely important. But there are a lot of business with mediocre skill using "connections" to justify their disproportionate split.
I've never heard of an engineer getting 90% of the equity (prior to future dilutions) while the well-connected MBA gets 10%, but the reverse isn't uncommon.
Unfortunately your attitude is the reason why most startups fail to get off the ground.
If you are going to start a company with someone you shouldn't even take a step unless you feel like this person could be your brother or sister. That means you have to be honest with each other about your weaknesses and strengths and accept them for what they are.
You should also have partnership agreements that allow you to buy the other one out if they are not pulling their weight.
From what you have written you are going to discount anyone that is non-technical but worse, you will constantly focus on what other team members are delivering to earn a seat at your table. It only takes on person on the team like that to ruin the whole thing.
There are a lot of "entrepreneurs" out there who have mediocre ideas, mediocre skill at the parts of business that actually matter (such as negotiation, marketing, and leadership), and minimal technical knowledge, but who justify disproportionate equity and authority splits based on "connections".
It can be an attractive proposition, when you're just starting out, to work for them. It's hard to tell a mediocre idea from a good one (Twitter seems mediocre on paper, but it worked) but connections obviously matter. If someone's genuinely well-connected, he'll be funded no matter what the idea is.
My advice is: don't work for them. If they were legitimately well-connected, they wouldn't need you to work for them on a low or zero salary.
The number of people in the world who are "well-connected" enough to be funded regardless of the idea are smaller than you think.
It would seem this way, but if you ever try to rent (much less buy) a place in the Bay Area or New York, you learn that there are a lot of rich fuckers kicking around.
I've never heard of an engineer getting 90% of the equity (prior to future dilutions) while the well-connected MBA gets 10%, but the reverse isn't uncommon.