ok here is me being unbiased
NODES DO MATTER:
bitcoin is a symbiotic relationship.
pools collate the tx data in a certain format.
the node network judge which block of data is a valid format of collated data and keeps that block if everything is valid/approved.
other nodes then see that a node has a new 'height' and requests that new accepted block. and as a snowball effect if the majority of the nodes have the same consensus rules, that block gets shared to the majority and that block gets set in stone.
by nodes holding a block and then pools building ontop of the most approved/valid previous block a single chain of good, valid accepted data becomes locked in and immutable.
if pools build upon blocks that are not majority accepted, they can find their newest attempt rejected because of the orphaning effect.
anyone shouting non-mining nodes do not matter, are only saying so because they dont want 'the opposition' gaining majority.
the problem with this is if both sides of the 'opposition' were to turn off their non mining nodes, then the only nodes of majority left are the miners nodes which then makes the mining nodes have more control because they become the majority.
for network safety sake dont let the 20 pools have the 'majority' otherwise they then control the network.
yes some will argue ' but if there are non-mining nodes setting rule A but pools want rule B it makes it harder/impossible for rule B to become law' well thats the point.
rule B should only become law if the community want rule B as a combined majority. it prevents pools changing the rules at a whim, it makes devs and pools actually fall inline and only change the rules if the new rules are good for the community as a majority.
this does not mean everyone should run 20+ nodes it just means dont let the decisions of rule changes become centralised
tl:dr;
its not just a mining game of who builds the biggest tower of blocks the fastest wins. where everyone then copies(like sheep) the fastest built tower..
its actually jenga.
who has the most stable and accepted highest tower of blocks without holes or risks of toppling over wins.
and its the node majority that get to poke holes in the tower until there is only one tower of strong immutable blocks that wont topple over