Yes I believe this is true. A capable general purpose SDR can do almost all the things that purpose built illegal device can do. What's protecting society is that figuring out how to do this on an expensive SDR is non-trivial. The illegal purpose built GPS-jamming devices just make it dead simple.

My take is that what makes the Flipper so revolutionary/disruptive is that it puts all these previously difficult to pentest systems (NFC/RFID and sub-GHz radio mainly), behind a dead simple UI.

One example is intercepting a particular NFC card's password to read its protected sectors. This requires reading the card's UID, then presenting that UID to a reader hooked knows that UID's password, recording the password it sends, then using that password on the NFC card.

Prior to the Flipper this NFC password interception was possible but difficult. The Flipper make this sort of NFC MITM attack dead easy. It's literally just 4-5 clicks in the UI. I've cloned my own hotel key cards this way. (And it's impractical to secretly clone someone else's card this way since it requires tapping the Flipper on the same card twice)