Why do RAM sticks need to be separated in the DIMM slots?

Why do RAM sticks need to be separated in the DIMM slots? dimm 2 slot The first PCIe x4 Slot supports the latest 25110 form factor Dual Channel DDR5：4*SMD DIMMs with AMD EXPO™ & Intel® XMP Memory Module Support dimm2 slot 2 x DIMM, Max 16GB, DDR3 Non-ECC, Un-buffered Memory; New UEFI BIOS & USB Features: 3x slot, Realtek Ethernet 23,600৳ 24,800

dimm2 slot It includes 16GB of SO-DIMM DDR4 3200MHz RAM, expandable up to 32GB with 2x SO-DIMM slots, and a 512GB PCIe NVMe SSD with an additional slot for

dimm 2 slot 2 riser card that uses a ninth DIMM-like slot on the right of the slot monsters, thanks to two PCIe slots sitting between the primary ones  Memory Technology Memory Technology DDR5 ; Speed · Speed · 5600MTs 5200MTs 4800MTs 3200MTs ; Form Factor Form Factor VLP DIMM