Why are you listening to 'some people'?? You should always only refer to the UKVI guidance and immigration rules.
The weblink I provided AND the Immigration Rules AND the Caseworker Guidance do NOT state that the Start Up visa can be counted! It would only count for ILR based on 10 years Long Residence.
Immigration Rule SW21.2 (click)
Qualifying period requirement for settlement as a Skilled Worker
SW 21.1. The applicant must have spent a continuous period of 5 years in the UK.
SW 21.2. The 5-year continuous period must consist of time with permission on any of, or any combination of, the following routes:
(a) Skilled Worker; or
(b) Global talent; or
(c) Innovator Founder; or
(d) T2 Minister of Religion; or
(e) International Sportsperson; or
(f) Representative of an Overseas Business; or
(g) as a Tier 1 Migrant, other than as a Tier 1 (Graduate Entrepreneur) Migrant; or
(h) Scale-up; or
Casework Guidance Page 54 (Click)
Qualifying period
The applicant must have spent a continuous period of 5 years in the UK, consisting
of time with permission in any of, or any combination of, the following routes:
• Skilled Worker
• Tier 2 (General)
• Global Talent
• Innovator Founder / Innovator
• T2 Minister of Religion / Tier 2 (Minister of Religion)
• International Sportsperson / T2 Sportsperson / Tier 2 (Sportsperson)
• Representative of an Overseas Business
• Tier 1 (Exceptional Talent)
• Tier 1 (Entrepreneur)
• Tier 1 (Investor)
• Tier 1 (General)