I think nostalgia is skewing your memory a bit when it comes to yesteryears. Under Atkinson, the idea of buying one of the worlds better players in their age and position was quite a farfetched one. We broke the English record for Bryan Robson as the most extravagant thing we did, and spent a big sum on Frank Stapleton, one of the best players from a team near the top. The only player of note we got from outside of Britain was Jesper Olsen, a nifty player but nowhere near the best in his position at the time. It pales in comparison to buying Maguire, Lukaku and Pogba for world record fees for their positions, in addition to Mkhitarian, Matic and Bruno.
Also under Ferguson, if you look at it in five year periods, doing something like buying player of the year from Bundesliga (Mkhi) or the most wanted young midfielder in the world (Pogba) was something that couldn’t have happened before we were fifteen years into his tenure. Only with the buys of Barthez, Veron and Van Nistelrooij did we begin to pick anything at all from the top end of the International market. At that time, we were recent CL winners and regular league winners.
Ferguson in his early days certainly didn’t buy ‘pretty much whoever he wanted’. In fact, part of his legacy was ingenious buys like Irwin, Schmeichel, Kanchelskis and Cantona. Granted, he did spend big (for England) on young talent like Pallister, Ince and Keane during the first five years, but nothing like these five last years.