Should every single student have a one-on-one dedicated paraprofessional of their own?
No, that's completely ridiculous and unnecessary. I say this as a mother to a child with Autism Spectrum Disorder who shares a para with one other child, and I also have a daughter with ADHD and one neurotypical child.
Some children need a dedicated para because they have physical disabilities that require them to have one. Some children have both physical and mental disabilities and require a dedicate para. Some, like my daughter, have the neurological disabilities and require a para to be in the room and attentive to her, but not dedicated just to her. In fact, if she had one dedicated only to her it would be detrimental to her education. She would let the para do more of her work than she should, and she's smarty pants enough to know how to get her para to do things for her because her para adores her. ;-)
My daughter's IEP requires that she's in a classroom with a teacher that has a minimum of experience with special needs students, but she often gets teachers that used to be SpEd teachers who specialized in ASD. It also requires that she be in a classroom that has its own para. Her IEP was adjusted this year because school funding was adjusted so that there are two paras in her classroom since there tend to be 3 or 4 kids in her class (which is mainstream) who are also special needs and require a para. None of the children requires a dedicated para.
The kids that require a dedicated para tend to spend their day in the actual Special Education classrooms. That will likely be the case until middle school and high school depending on the severity and type of disability and what's in their personalized IEP.
So after all that, what it comes down to is IEP's aka Individualized Education Plans. A child gets one if and when they have education and physical needs that require one, determined through a PPT aka Planning and Placement Team Meeting comprised of parents, teachers, therapists, social workers, school psychologists, the principal, student advocates, lawyers, etc. Needs determining whether a child requires a para depend on the evaluation a school does as well as the independent evaluation the parents have done in getting an official diagnosis.
It's not a matter of "should" every child have his or her own para. It's a matter of whether or not specific children NEED their own para. The school obtains the funds through submitting the paperwork to the State and Fed so that every child that NEEDS whatever supports in place in order to get an appropriate education to the best of that child's abilities is paid for and not on the parent's dime.
But people need to understand what a paraprofessional is. They are not a tutor. They are support staff to the school occupational therapists and speech therapists and other therapists that the student needs. They are also support staff for the teacher. They are physical support for the student as needed, and help guide the student in educational efforts without doing the work for them and adhering to whatever is in the student's IEP.