Separate rant for this! Let's count some reasons ...
1. If there is any layer that is actually between layer 4 (like TCP) and layer 7 (like HTTP or SMTP) ... *surely* it is TLS. But that's not a layer in the OSI model.
2. To double down on (1) ... have you *ever* seen layers 5 or 6 referred to? know what they are without looking? exactly? (also layers 5 and 6 make no real sense in a modern world).
3. In reality all sorts of "lower level" dependencies that the lower layers need like DNS, ARP, DHCP, PKI in fact run over much higher level layers. Neat layering is a lie!
4. Layers 1 and 2 and 3 are really like ... 6 or more intertwined layers. There's quite a lot between an IP or a MAC address and photons or electrons. Like just these 5 'hidden' layers: SDN, VLANs, MPLS, DWDM, OTN encryption are super common in today's world.
