> Only intel could come up with something which does not relate to anything.
This is wrong. You have to remember that the 8086 is (mostly) source code compatible to the 8080 (at least if you rename some registers - a simple search & replace) - though not binary compatoble. The assembler syntax for the Intel 8080 that Intel developed is ugly. But Zilog who developed the Z80 (which is binary compatible to the Intel 8080) devised a much better assembly language (as far as I know they had to use a different assembly language for legal reasons). For the 8086 Intel built on the ideas behind Zilog's assembly language. In Zilog assembler
(HL)
(IX+index)
(IY+index)
is used for accessing memory. Now replace the ( and ) by [ and ] and additionally keep in mind that the function of the register pair HL in 8080 roughly corresponds to bx (a "register pair" consisting of bh and bl) and it looks a lot like x86 assembler (IX and IY only exist in the Z80 and not in the 8080; but despite that the syntax for indexed adressing again reminds a lot of what one is used from x86 assembly in Intel syntax).
EDIT: Also the parameter order dst,src is the same as in Z80 assembler (but this order was already used in 8080 assembler so rather Zilog copied this order from 8080 assembler).
TLDR: The Intel syntax is related to Zilog Z80 assembly.
This is wrong. You have to remember that the 8086 is (mostly) source code compatible to the 8080 (at least if you rename some registers - a simple search & replace) - though not binary compatoble. The assembler syntax for the Intel 8080 that Intel developed is ugly. But Zilog who developed the Z80 (which is binary compatible to the Intel 8080) devised a much better assembly language (as far as I know they had to use a different assembly language for legal reasons). For the 8086 Intel built on the ideas behind Zilog's assembly language. In Zilog assembler
is used for accessing memory. Now replace the ( and ) by [ and ] and additionally keep in mind that the function of the register pair HL in 8080 roughly corresponds to bx (a "register pair" consisting of bh and bl) and it looks a lot like x86 assembler (IX and IY only exist in the Z80 and not in the 8080; but despite that the syntax for indexed adressing again reminds a lot of what one is used from x86 assembly in Intel syntax).EDIT: Also the parameter order dst,src is the same as in Z80 assembler (but this order was already used in 8080 assembler so rather Zilog copied this order from 8080 assembler).
TLDR: The Intel syntax is related to Zilog Z80 assembly.