I would say decentralized means that the power structure (whether it be mining in coins like Monero or Bitcoin, or in nodes like dash) is distributed enough that one party can't determine the outcome of votes
When you say "
power structure", in Dash the power structure is exactly where it is with every other coin:
- with
mining majority (and their choice of what protocol run run)
- with
commercial stakeholders (and their choice of whether to support the coin)
The "outcome of votes" as regards those executed by master nodes affects neither of those two. But then Dash has one additional "power structure" that other coins do not:
- a monthly budget that comprises 10% of the block reward
That gets spent on proposals to further the interests and development of the coin. The
ENTIRE coin supply counts towards the execution of that budget spend - not just people with masternodes. Anyone with the smallest amount of Dash can have their holding invested in Dash's reserve market and potentially influence that spend.
Right now, there are around 3700 collateralised masternodes. Of the coin supply that forms that collateral, around a few hundred (node's worth) are thought to be in the hands of so called "early adopters" or "instaminers" to use your terms. So even in this minority stockholding aspect of governance, they are well outnumbered and even if they weren't, they could still not overturn the
POW majority, still not overturn the
commercial stakeholding majority and still not overturn the
economic majority who actually endorse Dash's value in markets. (Which is why they have to act in the coin's best aggregate interests - not their own - if they want to protect their investment).
Finally, although I've argued that the 10% block reward budget governance is not an executive force in terms of technical and commercial protocols, it does do one other thing which is of huge strategic importance. That is to focus the voice of the coin holding population - whoever they may be - in such a way that market observers can judge the merits of their development priorities.
Whatever the outcome and however that voting population is made up, that is a huge dollop of transparency right there which other coins don't have because everyone can monitor the aspirations, concerns, priorities and achievements of the coin holding population who are putting their money where there mouth is
right out in the open.