MEMS oscillators not compatible with STM32F1 and STM32L1 series?

[Andrew Neil]

Just came across this post:

https://community.st.com/t5/stm32-mcus-products/oscillator-selection-for-stm32g4/m-p/571716/highlight/true#M217792

which quotes AN2867 saying that MEMS oscillators are, "compatible with all STM32 MCUs/MPUs, except for the STM32F1 and STM32L1 series." 
(my emphasis)

So what is it that makes the F1 and L1 unable to use MEMS oscillators?

[Bouraoui Chemli]

This could be due to the maximum input rise and fall time. For the STM32F1, it is 50 ns as indicated in Table 21 of the datasheet. In a MEMS oscillator, it can reach up to 100 or 200 ns.

[Andrew Neil]

It would be good if AN2867 stated the reason(s) - rather than just dismissing the F1 and L1