Can you dumb this down for someone who understands Internet networking (incl. internet backbone routing), and vaguely understands shared-medium networking like

Can you dumb this down for someone who understands Internet networking (incl. internet backbone routing), and vaguely understands shared-medium networking like wi-fi and cellular networks, but who knows next to nothing about coax, and especially nothing about fiber? What does a fiber loop (bus?) let you do hardware-wise, that a star topology wouldn't? Either way, you're running a piece of fiber to the home from somewhere, and connecting it to your network somehow; and I would assume that it's that connection that's inherently expensive, because of the equipment involved. In star topologies, that's a switch, or a hierarchy of switches. For a shared medium, that's a hub—or, I guess, some kind of direct splice, if that's somehow cheaper in TCO. Is the goal of using a loop, to avoid the cost of having neighbourhood-distribution-box optical network switches, instead directly splicing customers onto the ring, making the customer's fiber "part of" the shared medium of the loop, and then allowing customer equipment to directly push packets / transmission cells onto the loop? If so, why does it sound like you're implying that in a traditional FTTH star topology, there wouldn't be per-neighbourhood optical network switches, and instead only one wide-branching layer where all customers' lines terminate directly at one central location? That seems kind of ridiculous. Are optical switches really that expensive, that those are the only two options? Especially when neighbourhood-distribution-box optical switches would be relatively-low fan-in + relatively-low bandwidth, and therefore could be built to use simple low-frequency TDM circuit-switching protocols like coax's ATM? Also, is client-accessible fiber head-end equipment really trustworthy to do TDM (FDM?) onto a shared fiber medium, without ruining it for everyone else? We don't trust client equipment to do that on enterprise Ethernet networks (if we can at-all help it); we use switches instead of hubs, and we even put VLANs in place to further isolate flows in the merged path for QoS purposes. Is the difference just a matter of a fiber provider only certifying specific (presumably robust) equipment; and of that equipment not being coupled to power delivery issues of an arbitrary host device? Is that enough to get you peace-of-mind that your shared-medium network won't be being blasted with noise from new failing head-end equipment every few days?