I'm not sure if I'd completely agree with that statement. I think the reason most audio engineers use it isn't because it was designed for it nor is it because it's better for it. I think the reason most audio engineers use it is because most anyone who goes to any school for audio engineering is taught Pro Tools (and in a lot of cases ONLY Pro Tools) as part of the curriculum. Digidesign was smart by creating their own curriculum and making it available to colleges. The tide on the education front seems to have been shifting now as a lot of colleges are teaching Logic, Cubase, and others now as well.
While there is some truth in that I think there is also a lot of truth in what Muaguana says. Pro tools' dominance is not just from digi's buisiness savvy, as there was a time when pro tools was the ONLY system you could use in a big studio. Before computers had the power to record audio natively a pro tools HD setup was the only thing there was (along with radar, but thats a standalone system like tape).
As such the proffesional industry which adopted pro tools as the only computer based DAW useable has gotten used to it over the years and its become as much a standard tool as the tape machine was until the noughties. This has given digidesign a LOT of time to refine pro tools, make it work smoother, simpler, better etc while liasing with audio professionals who use it daily and demand the best performance.
In short, pro tools is simple, flexible and stable. It IS the first choice for engineers because there is so much 'engineering' to do on a big session you want your DAW to be simple and quick, which pro tools is. For the old hacks it also feels a bit more like a tape machine to use!
Logic on the other hand is the fast-gaining-popularity rival with everything to proove. It comes from midi manipulation as a background, not recording and has a history of innovation and flexibility. Its a MUCH MUCH bigger program that pro tools, with many more features and much more customizability. Its an amazing program but with all those features comes little bugs, weird conventions (look deep into naming the 4 elements of a normal audio track

) and sometimes things don't feel as fluid as PT in day to day editing.
It makes up for this in the time you save, however, by having an option to do ANYTHING!
It seems to me that the young professional engineers who have grown up with computers as they are today are more likely than ever to consider logic as a main DAW. For them, Logics increased depth is not daunting, and really quite exciting and may be a reason for them to choose it OVER PT. That said, I know many up and coming engineers who are PT freaks as well.
Of course, if you just use the surface of Logic, you don't need to see the complexity and its very easy to use. Conversly PT is a bit clunky and slow UNTIL you learn digi's key commands! To start with the relationship is switched around but with pro tools you very quickly hit a 'cap', with Logic you can explore for months and still find features you never use, or build custom mixers in the environment, or do silly things in the environment making patterns with the faders, or using the hyper editor to twist things around madly... or... ....
EDIT - oh yeah, I use PT at work (even though logic is available) and logic at home (even though PT is available!) pretty much becuase when I am at work I am in working 'engineer / producer' mode, and all the projects I do at home I am in 'musician / producer' mode. So yeah, PT for recording a band with no fuss, logic for getting down to creating music!