> would immediately be the highest possible level of breach
Obviously not true, in fact none of the companies I worked in that was the case. Now, if we're talking about somebody like network admin that may be more juicy, but in a large company rarely a single person has the "highest possible level".
> If you never worked at a company that took it seriously it is hard to imagine that there are people who do take it seriously
This sounds quite unsufferably smug, and unwarrantedly so. Yes, we get it, in Google they have access levels. Newsflash: this concept wasn't invented by Google. A lot of companies use it. Running code on engineers workstation does not give you keys to the whole castle. But it does get you into a first perimeter, after which you can do some recon, not available outside the big firewall, launch other things against corporate sites not available to mere mortals, look for "experimental" servers which are poorly secured because they're not production yet and are behind corporate firewall (that happened in pretty much ever company I've worked with), get their hands on some juicy browser cookies containing authorizations to some internal services, steal some code finally... There are a lot of interesting things a person can do with engineer's access and some of them may land a stepping stone to a next step access maybe. If you don't understand why such a thing may be important even without giving somebody the keys to the castle - maybe you don't know enough about how secure systems are built to smugly dismiss other people.