The blessing of Lk 7:23 is there because it would be very easy to get sidetracked by all the signs and wonders of Jesus (v21). The 'falling away' is thinking he was ONLY there to do signs and wonders, rather than the Gospel. V22 says he was doing what Isaiah had mentioned--preaching the Gospel to the poor, and there is no record that he was preaching a social gospel or handing out money.
In addition Luke regularly mentions the Gospel in 3:18 and 4:18 and 4:43. While healings or power over spirits was news (4:37) it was not the Gospel. The Gospel is found in the 'remarkable' healing where it is linked to a healing to prove his anointing, 5:24.' He is here to proclaim the time of God's grace, 4:19 (Is 61, cp 2 Cor 6:1, repeated).
Once again, he wasn't there to provide fish to all, even though that was a sign. he was there to show them how to catch men, 5:9.
They listeners are 'blessed if they do not fall away on account of me' means on account of all the signs and wonders. The disciples would be tested on that when he defined who he was in ch 9.
The same test is found in 9:43+. He does something about which the crowd marvels: they were all amazed at the greatness of God. But notice the next line: 'while they were marveling...' In other words, he had to do something to correct their tendency. It is about his dying. But it now gets hidden from them because all it will do is spur them to prevent it. They wanted a miracle god instead.
In 10:20, they are even told not to rejoice in their delegated power. So much for other gospels. It is now a 'good news' that they can't enjoy. But they can enjoy justification (being written in the names of heaven). I'm not even sure he is talking about his disciples in 10:21-24! Because justification through Christ's dying was 'hidden from them' and 'they did not understand.'