It sorta depends how you are defining 'supergroup.'
If it is a large DPM group (usually them + MBAs + venture capital) buying out multiple local 2, 3, 4, etc doc practices and starting new practices to funnel them all in to shared path, PT, orthotic lab, billing, mgmt, etc... that might be fine for your job quality. They could actually run things better, have a better system, staffing, etc. That is a windfall for the owner/partner(s) in the bought out group, and it is about a wash for associates (but their job quality could go up/down depending how it was beforehand).
If you are talking about the DPM "supergroup" ideas where many private practices try to simply stay largely autonomous yet pool resources (this is the much more common "supergroup"), then they are aiming to try to save on DME, supplies, keep more services in the group (orthotics, path, billing, etc), theoretically do group negotiation with payers, etc as was mentioned. That will be a slight expense for partner(s) and wash for associates at first. In the long term, it will be good or bad for the partners - entirely depends on how well the "supergroup" is run (accountants, billers, supply negotiations, etc). They often kinda start off as big talk and then not much actually happens. Down the line, it could help or hurt the partners, and based on how the partners do and choose to spread the wealth/loss, it could be good/bad for associate(s) too. Nothing happens fast.