Due to the needs to reduce complexity and have less vendors to deal with most companies use a limited amount of suppliers for datacenter equipment as well like

Due to the needs to reduce complexity and have less vendors to deal with most companies use a limited amount of suppliers for datacenter equipment as well like Dell or HPE or whatever. Data center customers care about support, vendor relationships, keeping complexity down, politics, reliability (= aversion to new products), lots of things. If anything the custom PC market is more focused around specs and prices solely.