- https://spca.bc.ca/faqs/indoor-cats-vs-outdoor-cats/

- https://www.animalhumanesociety.org/resource/are-outdoor-cat...

- https://www.banfield.com/en/Wellness-at-banfield/kitten-hub/...

And because I found it interesting, this study that aligns more with your point of view that concluded that cats who are allowed to roam do get more intellectual fulfillment than indoor-only cats on average: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10451177/

I would also like to note that I have seen firsthand how much cats infected with FIV and FeLV suffer when not actively treated, and all other considerations aside, I would never let my cats roam outside without a leash because of the prevalence of those diseases alone.