Untrue. With Debian you get to choose the type of the system you want to install.
Just deselect everything and you have very basic system without any extra packages.
That's an old picture, current Debian has "SSH server" in the list.
How does Gentoo give you any more control than say Debian?
Gentoo lets me pick combos of features and versions of software, whereas Debian forces me to use certain versions, very often badly packaged, with mostly unwanted dependencies. For example, for a very long time Debian was shipped with libldap-2.1 from openldap, and all software with LDAP dependencies were linked to libldap-2.1. The OpenLDAP packages though (like ldap-utils), were 2.4 and linked to libldap-2.4. So there were no ldapsearch or whatever linked to libldap-2.1 shipped, and debugging LDAP problems were a major PITA, and libldap2.1 was broken in so many ways, so there was plenty of problems. In general, Debian tends to ship with outdated and broken software that is not recommended by the upstream devs. And Debian support, which you of course have to use, since no upstream devs will bother with you as long as you run ancient versions that Debian have patched beyond FUBAR anyways, is a tiresome slow mess to deal with. So you end up building from source, and the build systems on Debian (yes, there are several) are far from elegant and easy to use.
For the record, I use Debian and Ubuntu professionally, I get paid for installing and maintaining Debian and Ubuntu systems, I get paid for packing software for Debian and Ubuntu systems. Do I enjoy it? Not much, it's quite often a PITA and reporting bugs is tiresome, they take forever (months and years) to get fixed. Privatly I run Gentoo on around 20-30 machines of a wide range of systems and architectures.