That is definitely troubling, however, I am unaware of your school's particular situation or location, but it is one of two things:
1. They lack funding than they actually lack intelligence. Chromebooks are nice for simple web browsing and only that. If you are using things like Microsoft Word, or various programs, go with a full computer. Some districts are standardized to have certain equipment so chances are it is the district's fault, not your individual school. Check the other schools in the district, if they haven't switched then it is your school individually. There is a town not far from where I grew up (the town I am referring to is Granite Bay, CA) and Granite Bay has all sorts of rich people (including celebrities) and many of the schools in Granite Bay had funding from local parents via Bonds, that they were able to get every student an iPad to keep indefinitely, a Microsoft Surface to use in art class, and an Oculus Rift for half the students in the school during recess (this was a K-6 school too, don't get me started on what the High School and Middle School kids had). My school district had computers that still ran Windows XP and had Microsoft Word 2003 on them, with most assignments done on paper and handed in because we lacked funding via state and local Bonds. Most state funds for education are used to fund Universities, states don't care much for 12th grade and below (mostly because they cannot make money with student loans off college students).
2. Some schools and/or districts are forced by law to comply with standardization laws that force them to use certain equipment to teach (again, usually determined by state funding to schools), this usually is done on a statewide basis, however it can be done in a County or City basis.