Not everyone can " progress up the structure" the very ethos of capitalism means that there is a loser for every winner
Providing there is constant growth, there are always more winners than losers.
Look to the USA
The USA is not somewhere I would wish to be poor, thats for sure! There are the facilities for individuals to lift themselves from poverty in the US, but there are more tempting opportunities (drink, drugs, malaise) to perpetuate it. If our 'mixed' system leans left 1% too much (for my liking), then theirs leans right 75% too much.
Is that a tacit admission that philanthropic capitalism alone cannot provide everything?
Absolutely. The wealth generated by the capitalist element provides for the socialist part. A 100% capitalist society could stand on its own feet, but considering there are a few people who physically can't contribute and take those steps up the ladder, it would be an unpleasant place to live. A wholly socialist society however cannot support itself.
some at the top some at the bottom yet we can all progress our way up?
Again, see growth.
The rest of your post
The thing is Junkyard, this is where I depart on a realist route and you continue wishfully on your idealogical one. Redistribution of wealth would not terminally end poverty. Injection of large amounts of cash to impoverished economies would kick off inflation, draining the new resource almost instantly. You'd then either return to the previous levels of wellbeing, or require money to be printed at an enormous and unsustainable rate to maintain.
Lets forget money for a minute. If you imagine the world economy as a gearbox, and the individuals within as the gears, what we have now is a situation where the resistance against the gears is just enough to limit us to a marginal, and (almost!) sustainable level of growth (~3%). In the west, you have some very big gears (rich), in the east you have some small ones (poor). You can change up gears, but like on your bike, that takes extra effort to achieve and you can only go one at a time.
If you made all the gears the same size however, the resistance to the system (natural growth) would be disproportionate to the level of work done by each gear, and the system would break.
Redistribution as an idea has been around forever, but will never, ever happen because those who understand know it won't benefit a single human being in the long term. (I'd also like to point out that my example of real people seeing real benefit and exceeding a widely acknowledged poverty measure is withstanding; I am yet to be shown a single instance of how preaching redistribution of wealth on the internet has benefited anyone. By that measure, my beliefs are more wholesome and caring than yours :))
You think if they had the money to buy these things they would be no better off in terms of welfare 
In the real world people born in wealthy nations live , on average for much longer than people born in poor nations....it is such a shame that reality bears no relation to your vision.
