D76 was designed to be replenished and gives it's best results when seasoned which happens when the level of Bromide in the working solution has built up. There is an ideal maximum level with MQ developers which was investigated by Axford & Kendal of Ilford as part of their research into PQ developers.

The Bromide is there in Adox Borax MQ, Agfa 44 (Agfa Ansco/GAF 17) etc as a starter, in the same way that RA-4 colour developers use a starter which adds Bromide/Iodide etc.

Agfa's version of D76 Agfa 19 is idenical except for the addition of 0.5-1g Potassium Bromide as a starter. Konica's version KD28 also uses 0.4g Bromide and Kodak themselves use it in one D76 variant.