Back then perceptrons (single neurons with engineered feature inputs) were a lot closer to cutting edge than they are now. As for why Matlab was used a lot: be

Back then perceptrons (single neurons with engineered feature inputs) were a lot closer to cutting edge than they are now. As for why Matlab was used a lot: because it comes "batteries included", I suspect. Probably the same reasons that Andrew Ng used it as the teaching language for his Stanford/Coursera Machine Learning course. Plus a lot of my lecturers had maths backgrounds.