There wasn't really an important 8086 box. The first IBM PC (1981) used the 8088. The first 8086 PCs were the discount models in the PS/2 line (April 1987), 3 years after the 80286 in the PC/AT (1984); so the 8086 was already obsolete by the time it was in a PC. And later that year (August 1987) it would be even more obsolete when an 80386DX PS/2 came out.
The one truly important 8086-based machine I can think of is the Japanese NEC PC-9801, so it would make some sense for someone to clone a machine like that. Though I'm not sure if I'd clone the original 9801 that kicked off the entire line or rather go for the much improved NEC V30 chip instead. (Which also powered Irem's M72 Arcade Board, which ran R-Type, and the latter M82/M84 boards that gave us R-Type II - though arguably, arcade boards aren't in the same category as home computers)
Was about to say that. The M24 was the one I much preferred using during that period, before AT (286) PCs started arriving (or made affordable).
There were other 8086 PCs around as well - I had a low-cost British one at home (IIRC it was called Advance 86 (EditUpd: That one was released near the end of 1983, way before any PS/2 line in 1987))
I had a Compaq Deskpro with an 8086. Noticeably faster than that XT. I bought it used, durt cheap when everyone else was upgrading to 286s. It worked quite well for quite some time. And the AT&T 6300 used an 8086 and the Toshiba T1200 had an 80C86. 8088's were definitely more popular among the cost-conscious, but it seemed after a couple years the clone manufacturers were making 8086 based systems for about the same price as IBM XTs.
I can think of one that was significant in the UK - the Amstrad PC1512, running off a NEC V30 processor, with 512KB RAM, easily upgradeable to 640K, with options for one or two floppies. I had one myself, along with a 32MB hard card fitted into the rear expansion slots.
If you think the only 'important' thing in computing at that time was the IBM PC, then maybe you think there were no 'important' 8086 boxes. There was a lot more going on at the time if you were actually there working at the time.
There were two variants of Model 30 in 1987. One with 8086 and another with the 80286. They were rehashed obsolete hardware with the ill-fated MCA which was supposed to be the future, but PCI won this particular battle.
As mentioned by a number of others in the comments, there definitely did exist 8086 based PC compatibles prior to 1987. No one is disputing the existence of this particular model.
