Am I to assume from all this that Facebook stores data on those who do not have an account with them?
Correct. It is safest to assume that they do have a highly detailed profile of you, all slurped illegally. Lets look at the ways they will have obtained that :
Firstly, there is the nagging to users to "just upload your contact list and we'll automatically invite them all to link up with you". Most users will have no clue that to upload such a list would be illegal itself, and it's just "so easy" to let FarceBork do all the work for them. So now they have (some subset) of name, phone number(s), email address(es), home address, work address(es), date of birth, date of marriage, spouse's name, and possibly more.
By powerful analytics, it's not hard to link multiple such entries - so if one person gives them you name, mobile number, home address & email, but another gives them name, mobile & work details, they can put them together.
Then there's all those websites that include FarceBork tracking stuff. They can, and do, follow you around the web - linking all (well a significant proportion of) those sites and pages you visit to some identifier. At some point you are bound to do something that will let them link this identifier to your profile - and bingo, they know who you are, who you interact with, what sites/pages you visit (and from that, what your interests are and what medical complaints you might have).
And then you have )so called) friends and family posting photos and comments that reference (and name) you. So now FarceBork have your photo and can (using face recognition) start picking you out in other photos even if you aren't named.
And yes, all this is done without any consent whatsoever. To see an example (from a few years ago), look up the details of Max Schrems case. He posts examples of the details they admitted to holding on him even without an account - and it was quite detailed.
Furthermore, there are sites where I've read the supposedly GDPR compliant page on cookies where I find advice that to opt out of such tracking I can follow a link and opt out. This falls over for two reasons: firstly it is not allowed to have an opt-out, secondly it just doesn't work if to opt out you have to create a FarceBork account - and hence both agree to the slurping and give them your details !
Light at the end of the tunnel, but basically FarceBork's business model (and a lot of Google's) is toast provided the regulators keep their nerve. In the long run, expect to see subscription options that will allow you to have "slurp free" access to services. Anything else could kill them as it's not allowed to make use of a service conditional on being slurped.