The debugger on your Nucleo can single-step your code, read every register, and show you the contents of memory — and it is blind to everything that happens outside the package. It will tell you, truthfully, that you wrote 0xA5 to the SPI data register. It cannot tell you whether 0xA5 left the pin, whether the clock that carried it was clean, whether the device on the other end was even powered.
A logic analyzer and an oscilloscope look like they answer the same question — "what happened on this wire" — and firmware engineers who own one tend to reach for it for everything, because a protocol decode is easier to read than a wobbly trace. They are not the same instrument. A logic analyzer's front end does one thing: at every sample instant, compare the voltage to a threshold and emit a 0 or a 1. Everything about how the signal got to that voltage — how fast, how far past it, whether it wobbled on the way — is discarded before the decoder ever sees a bit. An oscilloscope keeps that information. It is not a better logic analyzer; it answers a different class of question, and it is the only instrument in this folder that can.