Thinking that Form Feed erases the display is wrongly applying the semantics of paper terminals rather than video terminals.
On an old paper terminal, there was a Form Feed control character which caused the (usually continuous, fan-fold) paper to roll up to the start of the next sheet/form, and old lines would be on a long trail of paper hanging off the back of the terminal.
On video terminals from the 1960s, 1970s, and 1980s, there was a fixed size screen that could be erased, alongside explicitly moving the cursor back to the home position. Usually the Form Feed control character did not do this. It would just act like a newline, and there would be a different Erase Display control sequence for erasing the screen (c.f. Erase Display and Form Feed on the DEC VT series of video terminals).
Video terminals were not like some contemporary home computers's PRINT CHR$(12) in this respect.
Some modern terminal emulators have regressed from the video terminal paradigm. They have effectively reintroduced the old paper terminal semantics of having sheets of scrolled-off stuff hanging off the top of the terminal. When the emulated video terminal scrolls, scrolled-off stuff is pushed into a scrollback buffer, and erasing the display (normally) only erases the part that is below the bottom of the scrollback buffer.
Some GUI terminal emulators take this idea of going back to the old paper terminal semantics quite far. GNOME Terminal is one. It doesn't erase the screen like a video terminal at all, now. Ask it to Erase Display and it will perform a Form Feed instead, pushing everything into the scrollback buffer.
No, this is not the correct thing to do; clearly. Be aware that these are the very old paper terminal semantics, not the (less old) video terminal ones. You will not get them with other terminal emulators that are more in line with the latter, such as Konsole. Other terminal emulators you have to treat as video terminals rather than paper ones. Erase Display is not erroneously Form Feed, and Form Feed doesn't feed a bunch of pseudo-paper through.
Although it may seem like it from old 1970s ideas of bit-twiddling keyboards, ⎈ Control+L is not outputting Form Feed when you type it at a shell prompt.
It is a binding in your shell's command-line editing library (ZLE, or GNU Readline, or editline) that ends up in fact emitting the Erase Display control sequence, as if by tput clear.