This is true, but miners already control block size through soft caps.
Miners are fully capable of producing smaller blocks regardless of the max
block limit, with or without collusion. Arguably, there is no need to ever
reduce the max block size unless technology advances for some reason
reverse course - aka, WW3 takes a toll on the internet and the average
bandwidth available halves. The likelihood of significant technology
contraction in the near future seems rather unlikely and is more broadly
problematic for society than bitcoin specifically.

The only reason for reducing the max block limit other than technology
availability is if you think that this is what will produce the fee market,
which is back to an economic discussion - not a technology scaling
discussion.

On Tue, Sep 8, 2015 at 4:49 AM, Btc Drak via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> > but allow meaningful relief to transaction volume pressure in response
> to true market demand
>
> If blocksize can only increase then it's like a market that only goes
> up which is unrealistic. Transaction will volume ebb and flow
> significantly. Some people have been looking at transaction volume
> charts over time and all they can see is an exponential curve which
> they think will go on forever, yet nothing goes up forever and it will
> go through significant trend cycles (like everything does). If you
> dont want to hurt the fee market, the blocksize has to be elastic and
> allow contraction as well as expansion.
>