I haven't advocated against parties? However, having the party agree on everything would not be a good thing in the long run. What would be the point of elections at all if MPs have to blindly follow what they're told to do?
By advocating MPs should all be able to vote exactly how they want to on everything is effectively advocating against parties.
Here is what we have at the moment
1) The MPs for a party are told which way they should vote to agree with the party. Although they arae never forced to vote this way, if they don't it could have ramifications (explained to them in advance, a process called 'whipping').. ranging from light-weight stuff (they won't get their personal small almost insignificant amendments to their other bills - eg. 'Preston hospital doesn't get it's 15m maternity wing, so which way are you gonna vote on this unrelated bill Preston MP?') to more hardcore whipping tactics (not inviting them to join the cabinet (messing up their career), having them as a candidate for a 'tougher' constituency next time (risking their job), or even not having them as a party candidate next election (losing them their job unless they're tremendously popular with the locals so could stand as an independent)).
2) The MPs can still vote for whatever they want, but of course it's not a secret ballot or anything. No MP is ever FORCED to vote one way - just, er, strongly encouraged.
3) Some times you have 'backbench revolts' - when a load get together and say 'they can't screw with us all, lets ALL vote against our bosses together'. Which often works.
4) The PM or cabinet can declare a 'free vote'. This means any MP can vote for what they want without fear of repecussion. Normally after negotiation with the opposition to ensure they also offer a free vote. It means the government doesn't really know which way it wants to go, so they ask the house.
Now, if there is always no consequence for voting against your party, seriously, what is the point in having a thing called a 'political party'? There would be no point in it existing would there? As it is the same as a load of MPs standing as independents.
Also - I'm being deadly serious here .. what would be the point in having 1 person declared 'the prime minister'? He would have the same authority as everyone else - not more! Therefore the office may as well not exist. You see the problems?