Committed defconfigs for working configurations should never have CONFIG_EXPERIMENTAL set because the opens the doors for untested and incomplete configurations. Conversely, if there are released configurations that use features with dependencies on CONFIG_EXPERIMENTAL, then those configurations are in use and those dependencies should be removed:
graphics/vnc/server/Kconfig: Remove a dependency on CONFIG_EXPERIMENTAL
net/tcp/Kconfig: Remove a dependency on CONFIG_EXPERIMENTAL
wireless/bluetooth/Kconfig: Remove a dependency on CONFIG_EXPERIMENTAL
configs/lc823450-xgevk/audio/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/lc823450-xgevk/bt/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/lc823450-xgevk/ipl2/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/lc823450-xgevk/nsh/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/lc823450-xgevk/rndis/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/lc823450-xgevk/usb/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/lpcxpresso-lpc54628/netnsh/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/moxa/nsh/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/olimex-stm32-p407/module/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/photon/wlan/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/sabre-6quad/smp/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/sam4cmp-db/nsh/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/sama5d4-ek/elf/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/sama5d4-ek/knsh/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/samv71-xult/module/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/samv71-xult/vnc/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/samv71-xult/vnxwm/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/sim/bluetooth/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/sim/pf_ieee802154/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/sim/pktradio/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/sim/sixlowpan/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/sim/traveler/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/sim/userfs/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/stm32f4discovery/hciuart/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/stm32f4discovery/pseudoterm/defconfig: Remove CONFIG_EXPERIMENTAL=y
configs/teensy-3.x/usbnsh/defconfig: Remove CONFIG_EXPERIMENTAL=y