I think you have to understand the original intent of BLW and the context that it occurred in - the original book was published in 2008 and Gill Rapley was doing her HV work in the 70s, 80s and 90s - the culture of parenting, particularly of babies/toddlers was very different then. It was seen as a parent's job to get food into the child, cajoling "just one more, good girl" was normal, persuading them using little games like "Here comes the choo choo train!" was totally normal, expecting (older) children to clear their plate was normal, bribing with pudding, or punishment for refusing food was normal, force feeding was sometimes considered acceptable to some people, (I find this very shocking!) the idea that you'd let them run the show and decide whether to eat or not was just completely alien to most people. Gill, working as a HV, frequently encountered babies/young children who were fussy and refused to eat but they didn't have any physical problems - she felt that they were just reacting to the way they were being fed, which was adult-led and not taking their preferences or reactions into account.
That's why she came up with the idea of baby-led weaning and letting children have more control over whether they ate or not (similar to e.g. Ellyn Satter's Division of Responsibility, which was described in her book published in the 80s but seems less well known in the UK) and then this kind of naturally led to a place where - OK if we are letting the child have control over their food intake, do we even really need to spoon feed them purees at all or could they eat ordinary food? She cites her own master's degree, where she studied how babies ate when given control over the whole thing plus the change in guidance in 2002 (4 months to 6 months) as being her catalyst for this aspect of the BLW approach. Although she maintains she did not invent it and only gave it a name/studied it.
I think the entire culture is different now and the messaging we get around babies/parenting, including topics like feeding is very different. I don't know what other parents felt like in the 00s, but I had a baby in 2008 and it wouldn't have occurred to me to do anything else but be respectful of his experience and follow his lead when I was introducing food, even if I'd never heard of BLW which I did thanks to MN 
So the idea of letting babies be in control of what they eat and taking their feelings into account isn't especially radical or surprising any more. I think most people introduce solids in a respectful way, regardless of what method they use. The surprising and radical-seeming part is using whole foods rather than purees, and so that's what people assume BLW is. To an extent I would say that in 2024, that IS the distinction between traditional/puree weaning and BLW - because these days if you are bribing, cajoling, praising for amounts eaten, distracting a child so they'll eat, doing "three more pieces of brocolli to get pudding", expecting a cleared plate etc, people will say this is bad parenting, you're giving them a complex over food, and as for punishment for not eating, or force feeding - I'd call this abusive, and I think most parents today would.
So BLW becomes a shorthand for "solid foods a 6m+ baby can handle" and then, yeah, it makes absolute sense that you can do a mixture.
I do get the pedantry over specific definitions (you mentioned a spectrum 🤐) but when the majority of people have started using a word to mean a different definition, it is a bit confusing if you insist on sticking to the original definition when 99% of people are using it to mean something else.