Actually, your dates are a bit off. The Beutler developer goes back at least to the early 50s. It was, indeed, popular with the early Adox "thin emulsion" films of the mid 50s. It was never intended to be a fine grain developer, but the Adox films, particularly KB14 and KB17, had fine enough grain for that not to be a problem (then). The developer is a fine example of a compensating developer. The dilution helps to control the contrast, which was quite high with these films. It also gives a strong Mackie line for sharpness effects.