I have used boost for several big projects with an extended code base and it
always creates various issues with the build. If you use it extensively, you will realize that certain parts are not header only; you will need to link it with libraries (think threads or filesystem libraries).
I use C++ for portability accross several platforms and boost always seems to have a completely different naming convention in each platform. Upgrading between versions e.g. 1.48 to 1.51 will very likely require code changes since it is not uncommon to break API contracts across versions.
I have amazing C++ developers with decades of experience that would quit on the spot if I forced them to use boost - and I wouldnt blame them.
I can rant forever.
New versions of C++ have things that used to make boost essential, but now that later C++ standards support lots of those concepts, I am happily boost-free. Boost is a huge negative, so you would need to be really amazing for me to even consider bringing back a dependency that has only brought me so much pain in the past.