You're simply empirically wrong [about the 'amount' of money that represents, whether it is large enough to make a substantial difference], and your anchors[1] are not only irrelevant and misleading in an early-stage context, but extremely toxic.[2] What was Google's first check in the amount of? $100K. It was a ton of money. As Wikipedia points out, "The first funding for Google as a company was secured in August 1998 in the form of a US$100,000 contribution from Andy Bechtolsheim, co-founder of Sun Microsystems, given to a corporation which did not yet exist." They used that to raise "On June 7, 1999, a round of equity funding totalling $25 million", about 10 months later. Pop quiz. Which was more money, the $100K in the first context or the $25M in the second? Well, as I've heard they never did spend much of that $25M, it sat in Google's bank account while they grew and raised further rounds....
But that $100K? That was a ton of money.
Basically, you are wrong that it was not a ton of money, your anchors and comparisons are toxic and misleading, and if he had not cut that check then Larry and Sergey would not have created Google. That is what actual reality shows us.
You simply do an incredible disservice to all early-stage startups by talking in these terms.
I gave you several actual examples of far less than $120K being a ton of money in an early-stage context. As little as $5000 being a ton of money. I also specifically stated that if, say, $20K, weren't a lot of money, then it would make no difference empirically if YCombinator did not actually pay that cash. And YC companies wouldn't have either relied on or even actually spent that cash. But it does make a difference, and they did.
As I specifically point out: your FTE expenses are completely irrelevant, and even part (less than 100%) of the after-tax portion of a single FTE salary is a ton of money. (In an early-stage context.)
To imply otherwise does a huge disservice to all first-time, early-stage founders everywhere. The very idea is toxic and needs to die.
[1] The meaning of anchor I use is: http://en.wikipedia.org/wiki/Anchoring
[2] Your figures both about (1) the cost to the company of a fully loaded FTE senior engineer and (2) the amount that a good freelancer can generate above living expenses in a year, are irrelevant and do not need to be argued. I will grant both as irrelevant to the discussion.